From 5b7c4cabbb65f5c469464da6c5f614cbd7f730f2 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Tue, 21 Feb 2023 18:24:12 -0800 Subject: Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next Pull networking updates from Jakub Kicinski: "Core: - Add dedicated kmem_cache for typical/small skb->head, avoid having to access struct page at kfree time, and improve memory use. - Introduce sysctl to set default RPS configuration for new netdevs. - Define Netlink protocol specification format which can be used to describe messages used by each family and auto-generate parsers. Add tools for generating kernel data structures and uAPI headers. - Expose all net/core sysctls inside netns. - Remove 4s sleep in netpoll if carrier is instantly detected on boot. - Add configurable limit of MDB entries per port, and port-vlan. - Continue populating drop reasons throughout the stack. - Retire a handful of legacy Qdiscs and classifiers. Protocols: - Support IPv4 big TCP (TSO frames larger than 64kB). - Add IP_LOCAL_PORT_RANGE socket option, to control local port range on socket by socket basis. - Track and report in procfs number of MPTCP sockets used. - Support mixing IPv4 and IPv6 flows in the in-kernel MPTCP path manager. - IPv6: don't check net.ipv6.route.max_size and rely on garbage collection to free memory (similarly to IPv4). - Support Penultimate Segment Pop (PSP) flavor in SRv6 (RFC8986). - ICMP: add per-rate limit counters. - Add support for user scanning requests in ieee802154. - Remove static WEP support. - Support minimal Wi-Fi 7 Extremely High Throughput (EHT) rate reporting. - WiFi 7 EHT channel puncturing support (client & AP). BPF: - Add a rbtree data structure following the "next-gen data structure" precedent set by recently added linked list, that is, by using kfunc + kptr instead of adding a new BPF map type. - Expose XDP hints via kfuncs with initial support for RX hash and timestamp metadata. - Add BPF_F_NO_TUNNEL_KEY extension to bpf_skb_set_tunnel_key to better support decap on GRE tunnel devices not operating in collect metadata. - Improve x86 JIT's codegen for PROBE_MEM runtime error checks. - Remove the need for trace_printk_lock for bpf_trace_printk and bpf_trace_vprintk helpers. - Extend libbpf's bpf_tracing.h support for tracing arguments of kprobes/uprobes and syscall as a special case. - Significantly reduce the search time for module symbols by livepatch and BPF. - Enable cpumasks to be used as kptrs, which is useful for tracing programs tracking which tasks end up running on which CPUs in different time intervals. - Add support for BPF trampoline on s390x and riscv64. - Add capability to export the XDP features supported by the NIC. - Add __bpf_kfunc tag for marking kernel functions as kfuncs. - Add cgroup.memory=nobpf kernel parameter option to disable BPF memory accounting for container environments. Netfilter: - Remove the CLUSTERIP target. It has been marked as obsolete for years, and we still have WARN splats wrt races of the out-of-band /proc interface installed by this target. - Add 'destroy' commands to nf_tables. They are identical to the existing 'delete' commands, but do not return an error if the referenced object (set, chain, rule...) did not exist. Driver API: - Improve cpumask_local_spread() locality to help NICs set the right IRQ affinity on AMD platforms. - Separate C22 and C45 MDIO bus transactions more clearly. - Introduce new DCB table to control DSCP rewrite on egress. - Support configuration of Physical Layer Collision Avoidance (PLCA) Reconciliation Sublayer (RS) (802.3cg-2019). Modern version of shared medium Ethernet. - Support for MAC Merge layer (IEEE 802.3-2018 clause 99). Allowing preemption of low priority frames by high priority frames. - Add support for controlling MACSec offload using netlink SET. - Rework devlink instance refcounts to allow registration and de-registration under the instance lock. Split the code into multiple files, drop some of the unnecessarily granular locks and factor out common parts of netlink operation handling. - Add TX frame aggregation parameters (for USB drivers). - Add a new attr TCA_EXT_WARN_MSG to report TC (offload) warning messages with notifications for debug. - Allow offloading of UDP NEW connections via act_ct. - Add support for per action HW stats in TC. - Support hardware miss to TC action (continue processing in SW from a specific point in the action chain). - Warn if old Wireless Extension user space interface is used with modern cfg80211/mac80211 drivers. Do not support Wireless Extensions for Wi-Fi 7 devices at all. Everyone should switch to using nl80211 interface instead. - Improve the CAN bit timing configuration. Use extack to return error messages directly to user space, update the SJW handling, including the definition of a new default value that will benefit CAN-FD controllers, by increasing their oscillator tolerance. New hardware / drivers: - Ethernet: - nVidia BlueField-3 support (control traffic driver) - Ethernet support for imx93 SoCs - Motorcomm yt8531 gigabit Ethernet PHY - onsemi NCN26000 10BASE-T1S PHY (with support for PLCA) - Microchip LAN8841 PHY (incl. cable diagnostics and PTP) - Amlogic gxl MDIO mux - WiFi: - RealTek RTL8188EU (rtl8xxxu) - Qualcomm Wi-Fi 7 devices (ath12k) - CAN: - Renesas R-Car V4H Drivers: - Bluetooth: - Set Per Platform Antenna Gain (PPAG) for Intel controllers. - Ethernet NICs: - Intel (1G, igc): - support TSN / Qbv / packet scheduling features of i226 model - Intel (100G, ice): - use GNSS subsystem instead of TTY - multi-buffer XDP support - extend support for GPIO pins to E823 devices - nVidia/Mellanox: - update the shared buffer configuration on PFC commands - implement PTP adjphase function for HW offset control - TC support for Geneve and GRE with VF tunnel offload - more efficient crypto key management method - multi-port eswitch support - Netronome/Corigine: - add DCB IEEE support - support IPsec offloading for NFP3800 - Freescale/NXP (enetc): - support XDP_REDIRECT for XDP non-linear buffers - improve reconfig, avoid link flap and waiting for idle - support MAC Merge layer - Other NICs: - sfc/ef100: add basic devlink support for ef100 - ionic: rx_push mode operation (writing descriptors via MMIO) - bnxt: use the auxiliary bus abstraction for RDMA - r8169: disable ASPM and reset bus in case of tx timeout - cpsw: support QSGMII mode for J721e CPSW9G - cpts: support pulse-per-second output - ngbe: add an mdio bus driver - usbnet: optimize usbnet_bh() by avoiding unnecessary queuing - r8152: handle devices with FW with NCM support - amd-xgbe: support 10Mbps, 2.5GbE speeds and rx-adaptation - virtio-net: support multi buffer XDP - virtio/vsock: replace virtio_vsock_pkt with sk_buff - tsnep: XDP support - Ethernet high-speed switches: - nVidia/Mellanox (mlxsw): - add support for latency TLV (in FW control messages) - Microchip (sparx5): - separate explicit and implicit traffic forwarding rules, make the implicit rules always active - add support for egress DSCP rewrite - IS0 VCAP support (Ingress Classification) - IS2 VCAP filters (protos, L3 addrs, L4 ports, flags, ToS etc.) - ES2 VCAP support (Egress Access Control) - support for Per-Stream Filtering and Policing (802.1Q, 8.6.5.1) - Ethernet embedded switches: - Marvell (mv88e6xxx): - add MAB (port auth) offload support - enable PTP receive for mv88e6390 - NXP (ocelot): - support MAC Merge layer - support for the the vsc7512 internal copper phys - Microchip: - lan9303: convert to PHYLINK - lan966x: support TC flower filter statistics - lan937x: PTP support for KSZ9563/KSZ8563 and LAN937x - lan937x: support Credit Based Shaper configuration - ksz9477: support Energy Efficient Ethernet - other: - qca8k: convert to regmap read/write API, use bulk operations - rswitch: Improve TX timestamp accuracy - Intel WiFi (iwlwifi): - EHT (Wi-Fi 7) rate reporting - STEP equalizer support: transfer some STEP (connection to radio on platforms with integrated wifi) related parameters from the BIOS to the firmware. - Qualcomm 802.11ax WiFi (ath11k): - IPQ5018 support - Fine Timing Measurement (FTM) responder role support - channel 177 support - MediaTek WiFi (mt76): - per-PHY LED support - mt7996: EHT (Wi-Fi 7) support - Wireless Ethernet Dispatch (WED) reset support - switch to using page pool allocator - RealTek WiFi (rtw89): - support new version of Bluetooth co-existance - Mobile: - rmnet: support TX aggregation" * tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1872 commits) page_pool: add a comment explaining the fragment counter usage net: ethtool: fix __ethtool_dev_mm_supported() implementation ethtool: pse-pd: Fix double word in comments xsk: add linux/vmalloc.h to xsk.c sefltests: netdevsim: wait for devlink instance after netns removal selftest: fib_tests: Always cleanup before exit net/mlx5e: Align IPsec ASO result memory to be as required by hardware net/mlx5e: TC, Set CT miss to the specific ct action instance net/mlx5e: Rename CHAIN_TO_REG to MAPPED_OBJ_TO_REG net/mlx5: Refactor tc miss handling to a single function net/mlx5: Kconfig: Make tc offload depend on tc skb extension net/sched: flower: Support hardware miss to tc action net/sched: flower: Move filter handle initialization earlier net/sched: cls_api: Support hardware miss to tc action net/sched: Rename user cookie and act cookie sfc: fix builds without CONFIG_RTC_LIB sfc: clean up some inconsistent indentings net/mlx4_en: Introduce flexible array to silence overflow warning net: lan966x: Fix possible deadlock inside PTP net/ulp: Remove redundant ->clone() test in inet_clone_ulp(). ... --- Documentation/power/swsusp.rst | 503 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 503 insertions(+) create mode 100644 Documentation/power/swsusp.rst (limited to 'Documentation/power/swsusp.rst') diff --git a/Documentation/power/swsusp.rst b/Documentation/power/swsusp.rst new file mode 100644 index 000000000..8524f079e --- /dev/null +++ b/Documentation/power/swsusp.rst @@ -0,0 +1,503 @@ +============ +Swap suspend +============ + +Some warnings, first. + +.. warning:: + + **BIG FAT WARNING** + + If you touch anything on disk between suspend and resume... + ...kiss your data goodbye. + + If you do resume from initrd after your filesystems are mounted... + ...bye bye root partition. + + [this is actually same case as above] + + If you have unsupported ( ) devices using DMA, you may have some + problems. If your disk driver does not support suspend... (IDE does), + it may cause some problems, too. If you change kernel command line + between suspend and resume, it may do something wrong. If you change + your hardware while system is suspended... well, it was not good idea; + but it will probably only crash. + + ( ) suspend/resume support is needed to make it safe. + + If you have any filesystems on USB devices mounted before software suspend, + they won't be accessible after resume and you may lose data, as though + you have unplugged the USB devices with mounted filesystems on them; + see the FAQ below for details. (This is not true for more traditional + power states like "standby", which normally don't turn USB off.) + +Swap partition: + You need to append resume=/dev/your_swap_partition to kernel command + line or specify it using /sys/power/resume. + +Swap file: + If using a swapfile you can also specify a resume offset using + resume_offset= on the kernel command line or specify it + in /sys/power/resume_offset. + +After preparing then you suspend by:: + + echo shutdown > /sys/power/disk; echo disk > /sys/power/state + +- If you feel ACPI works pretty well on your system, you might try:: + + echo platform > /sys/power/disk; echo disk > /sys/power/state + +- If you would like to write hibernation image to swap and then suspend + to RAM (provided your platform supports it), you can try:: + + echo suspend > /sys/power/disk; echo disk > /sys/power/state + +- If you have SATA disks, you'll need recent kernels with SATA suspend + support. For suspend and resume to work, make sure your disk drivers + are built into kernel -- not modules. [There's way to make + suspend/resume with modular disk drivers, see FAQ, but you probably + should not do that.] + +If you want to limit the suspend image size to N bytes, do:: + + echo N > /sys/power/image_size + +before suspend (it is limited to around 2/5 of available RAM by default). + +- The resume process checks for the presence of the resume device, + if found, it then checks the contents for the hibernation image signature. + If both are found, it resumes the hibernation image. + +- The resume process may be triggered in two ways: + + 1) During lateinit: If resume=/dev/your_swap_partition is specified on + the kernel command line, lateinit runs the resume process. If the + resume device has not been probed yet, the resume process fails and + bootup continues. + 2) Manually from an initrd or initramfs: May be run from + the init script by using the /sys/power/resume file. It is vital + that this be done prior to remounting any filesystems (even as + read-only) otherwise data may be corrupted. + +Article about goals and implementation of Software Suspend for Linux +==================================================================== + +Author: Gábor Kuti +Last revised: 2003-10-20 by Pavel Machek + +Idea and goals to achieve +------------------------- + +Nowadays it is common in several laptops that they have a suspend button. It +saves the state of the machine to a filesystem or to a partition and switches +to standby mode. Later resuming the machine the saved state is loaded back to +ram and the machine can continue its work. It has two real benefits. First we +save ourselves the time machine goes down and later boots up, energy costs +are real high when running from batteries. The other gain is that we don't have +to interrupt our programs so processes that are calculating something for a long +time shouldn't need to be written interruptible. + +swsusp saves the state of the machine into active swaps and then reboots or +powerdowns. You must explicitly specify the swap partition to resume from with +`resume=` kernel option. If signature is found it loads and restores saved +state. If the option `noresume` is specified as a boot parameter, it skips +the resuming. If the option `hibernate=nocompress` is specified as a boot +parameter, it saves hibernation image without compression. + +In the meantime while the system is suspended you should not add/remove any +of the hardware, write to the filesystems, etc. + +Sleep states summary +==================== + +There are three different interfaces you can use, /proc/acpi should +work like this: + +In a really perfect world:: + + echo 1 > /proc/acpi/sleep # for standby + echo 2 > /proc/acpi/sleep # for suspend to ram + echo 3 > /proc/acpi/sleep # for suspend to ram, but with more power + # conservative + echo 4 > /proc/acpi/sleep # for suspend to disk + echo 5 > /proc/acpi/sleep # for shutdown unfriendly the system + +and perhaps:: + + echo 4b > /proc/acpi/sleep # for suspend to disk via s4bios + +Frequently Asked Questions +========================== + +Q: + well, suspending a server is IMHO a really stupid thing, + but... (Diego Zuccato): + +A: + You bought new UPS for your server. How do you install it without + bringing machine down? Suspend to disk, rearrange power cables, + resume. + + You have your server on UPS. Power died, and UPS is indicating 30 + seconds to failure. What do you do? Suspend to disk. + + +Q: + Maybe I'm missing something, but why don't the regular I/O paths work? + +A: + We do use the regular I/O paths. However we cannot restore the data + to its original location as we load it. That would create an + inconsistent kernel state which would certainly result in an oops. + Instead, we load the image into unused memory and then atomically copy + it back to it original location. This implies, of course, a maximum + image size of half the amount of memory. + + There are two solutions to this: + + * require half of memory to be free during suspend. That way you can + read "new" data onto free spots, then cli and copy + + * assume we had special "polling" ide driver that only uses memory + between 0-640KB. That way, I'd have to make sure that 0-640KB is free + during suspending, but otherwise it would work... + + suspend2 shares this fundamental limitation, but does not include user + data and disk caches into "used memory" by saving them in + advance. That means that the limitation goes away in practice. + +Q: + Does linux support ACPI S4? + +A: + Yes. That's what echo platform > /sys/power/disk does. + +Q: + What is 'suspend2'? + +A: + suspend2 is 'Software Suspend 2', a forked implementation of + suspend-to-disk which is available as separate patches for 2.4 and 2.6 + kernels from swsusp.sourceforge.net. It includes support for SMP, 4GB + highmem and preemption. It also has a extensible architecture that + allows for arbitrary transformations on the image (compression, + encryption) and arbitrary backends for writing the image (eg to swap + or an NFS share[Work In Progress]). Questions regarding suspend2 + should be sent to the mailing list available through the suspend2 + website, and not to the Linux Kernel Mailing List. We are working + toward merging suspend2 into the mainline kernel. + +Q: + What is the freezing of tasks and why are we using it? + +A: + The freezing of tasks is a mechanism by which user space processes and some + kernel threads are controlled during hibernation or system-wide suspend (on + some architectures). See freezing-of-tasks.txt for details. + +Q: + What is the difference between "platform" and "shutdown"? + +A: + shutdown: + save state in linux, then tell bios to powerdown + + platform: + save state in linux, then tell bios to powerdown and blink + "suspended led" + + "platform" is actually right thing to do where supported, but + "shutdown" is most reliable (except on ACPI systems). + +Q: + I do not understand why you have such strong objections to idea of + selective suspend. + +A: + Do selective suspend during runtime power management, that's okay. But + it's useless for suspend-to-disk. (And I do not see how you could use + it for suspend-to-ram, I hope you do not want that). + + Lets see, so you suggest to + + * SUSPEND all but swap device and parents + * Snapshot + * Write image to disk + * SUSPEND swap device and parents + * Powerdown + + Oh no, that does not work, if swap device or its parents uses DMA, + you've corrupted data. You'd have to do + + * SUSPEND all but swap device and parents + * FREEZE swap device and parents + * Snapshot + * UNFREEZE swap device and parents + * Write + * SUSPEND swap device and parents + + Which means that you still need that FREEZE state, and you get more + complicated code. (And I have not yet introduce details like system + devices). + +Q: + There don't seem to be any generally useful behavioral + distinctions between SUSPEND and FREEZE. + +A: + Doing SUSPEND when you are asked to do FREEZE is always correct, + but it may be unnecessarily slow. If you want your driver to stay simple, + slowness may not matter to you. It can always be fixed later. + + For devices like disk it does matter, you do not want to spindown for + FREEZE. + +Q: + After resuming, system is paging heavily, leading to very bad interactivity. + +A: + Try running:: + + cat /proc/[0-9]*/maps | grep / | sed 's:.* /:/:' | sort -u | while read file + do + test -f "$file" && cat "$file" > /dev/null + done + + after resume. swapoff -a; swapon -a may also be useful. + +Q: + What happens to devices during swsusp? They seem to be resumed + during system suspend? + +A: + That's correct. We need to resume them if we want to write image to + disk. Whole sequence goes like + + **Suspend part** + + running system, user asks for suspend-to-disk + + user processes are stopped + + suspend(PMSG_FREEZE): devices are frozen so that they don't interfere + with state snapshot + + state snapshot: copy of whole used memory is taken with interrupts + disabled + + resume(): devices are woken up so that we can write image to swap + + write image to swap + + suspend(PMSG_SUSPEND): suspend devices so that we can power off + + turn the power off + + **Resume part** + + (is actually pretty similar) + + running system, user asks for suspend-to-disk + + user processes are stopped (in common case there are none, + but with resume-from-initrd, no one knows) + + read image from disk + + suspend(PMSG_FREEZE): devices are frozen so that they don't interfere + with image restoration + + image restoration: rewrite memory with image + + resume(): devices are woken up so that system can continue + + thaw all user processes + +Q: + What is this 'Encrypt suspend image' for? + +A: + First of all: it is not a replacement for dm-crypt encrypted swap. + It cannot protect your computer while it is suspended. Instead it does + protect from leaking sensitive data after resume from suspend. + + Think of the following: you suspend while an application is running + that keeps sensitive data in memory. The application itself prevents + the data from being swapped out. Suspend, however, must write these + data to swap to be able to resume later on. Without suspend encryption + your sensitive data are then stored in plaintext on disk. This means + that after resume your sensitive data are accessible to all + applications having direct access to the swap device which was used + for suspend. If you don't need swap after resume these data can remain + on disk virtually forever. Thus it can happen that your system gets + broken in weeks later and sensitive data which you thought were + encrypted and protected are retrieved and stolen from the swap device. + To prevent this situation you should use 'Encrypt suspend image'. + + During suspend a temporary key is created and this key is used to + encrypt the data written to disk. When, during resume, the data was + read back into memory the temporary key is destroyed which simply + means that all data written to disk during suspend are then + inaccessible so they can't be stolen later on. The only thing that + you must then take care of is that you call 'mkswap' for the swap + partition used for suspend as early as possible during regular + boot. This asserts that any temporary key from an oopsed suspend or + from a failed or aborted resume is erased from the swap device. + + As a rule of thumb use encrypted swap to protect your data while your + system is shut down or suspended. Additionally use the encrypted + suspend image to prevent sensitive data from being stolen after + resume. + +Q: + Can I suspend to a swap file? + +A: + Generally, yes, you can. However, it requires you to use the "resume=" and + "resume_offset=" kernel command line parameters, so the resume from a swap + file cannot be initiated from an initrd or initramfs image. See + swsusp-and-swap-files.txt for details. + +Q: + Is there a maximum system RAM size that is supported by swsusp? + +A: + It should work okay with highmem. + +Q: + Does swsusp (to disk) use only one swap partition or can it use + multiple swap partitions (aggregate them into one logical space)? + +A: + Only one swap partition, sorry. + +Q: + If my application(s) causes lots of memory & swap space to be used + (over half of the total system RAM), is it correct that it is likely + to be useless to try to suspend to disk while that app is running? + +A: + No, it should work okay, as long as your app does not mlock() + it. Just prepare big enough swap partition. + +Q: + What information is useful for debugging suspend-to-disk problems? + +A: + Well, last messages on the screen are always useful. If something + is broken, it is usually some kernel driver, therefore trying with as + little as possible modules loaded helps a lot. I also prefer people to + suspend from console, preferably without X running. Booting with + init=/bin/bash, then swapon and starting suspend sequence manually + usually does the trick. Then it is good idea to try with latest + vanilla kernel. + +Q: + How can distributions ship a swsusp-supporting kernel with modular + disk drivers (especially SATA)? + +A: + Well, it can be done, load the drivers, then do echo into + /sys/power/resume file from initrd. Be sure not to mount + anything, not even read-only mount, or you are going to lose your + data. + +Q: + How do I make suspend more verbose? + +A: + If you want to see any non-error kernel messages on the virtual + terminal the kernel switches to during suspend, you have to set the + kernel console loglevel to at least 4 (KERN_WARNING), for example by + doing:: + + # save the old loglevel + read LOGLEVEL DUMMY < /proc/sys/kernel/printk + # set the loglevel so we see the progress bar. + # if the level is higher than needed, we leave it alone. + if [ $LOGLEVEL -lt 5 ]; then + echo 5 > /proc/sys/kernel/printk + fi + + IMG_SZ=0 + read IMG_SZ < /sys/power/image_size + echo -n disk > /sys/power/state + RET=$? + # + # the logic here is: + # if image_size > 0 (without kernel support, IMG_SZ will be zero), + # then try again with image_size set to zero. + if [ $RET -ne 0 -a $IMG_SZ -ne 0 ]; then # try again with minimal image size + echo 0 > /sys/power/image_size + echo -n disk > /sys/power/state + RET=$? + fi + + # restore previous loglevel + echo $LOGLEVEL > /proc/sys/kernel/printk + exit $RET + +Q: + Is this true that if I have a mounted filesystem on a USB device and + I suspend to disk, I can lose data unless the filesystem has been mounted + with "sync"? + +A: + That's right ... if you disconnect that device, you may lose data. + In fact, even with "-o sync" you can lose data if your programs have + information in buffers they haven't written out to a disk you disconnect, + or if you disconnect before the device finished saving data you wrote. + + Software suspend normally powers down USB controllers, which is equivalent + to disconnecting all USB devices attached to your system. + + Your system might well support low-power modes for its USB controllers + while the system is asleep, maintaining the connection, using true sleep + modes like "suspend-to-RAM" or "standby". (Don't write "disk" to the + /sys/power/state file; write "standby" or "mem".) We've not seen any + hardware that can use these modes through software suspend, although in + theory some systems might support "platform" modes that won't break the + USB connections. + + Remember that it's always a bad idea to unplug a disk drive containing a + mounted filesystem. That's true even when your system is asleep! The + safest thing is to unmount all filesystems on removable media (such USB, + Firewire, CompactFlash, MMC, external SATA, or even IDE hotplug bays) + before suspending; then remount them after resuming. + + There is a work-around for this problem. For more information, see + Documentation/driver-api/usb/persist.rst. + +Q: + Can I suspend-to-disk using a swap partition under LVM? + +A: + Yes and No. You can suspend successfully, but the kernel will not be able + to resume on its own. You need an initramfs that can recognize the resume + situation, activate the logical volume containing the swap volume (but not + touch any filesystems!), and eventually call:: + + echo -n "$major:$minor" > /sys/power/resume + + where $major and $minor are the respective major and minor device numbers of + the swap volume. + + uswsusp works with LVM, too. See http://suspend.sourceforge.net/ + +Q: + I upgraded the kernel from 2.6.15 to 2.6.16. Both kernels were + compiled with the similar configuration files. Anyway I found that + suspend to disk (and resume) is much slower on 2.6.16 compared to + 2.6.15. Any idea for why that might happen or how can I speed it up? + +A: + This is because the size of the suspend image is now greater than + for 2.6.15 (by saving more data we can get more responsive system + after resume). + + There's the /sys/power/image_size knob that controls the size of the + image. If you set it to 0 (eg. by echo 0 > /sys/power/image_size as + root), the 2.6.15 behavior should be restored. If it is still too + slow, take a look at suspend.sf.net -- userland suspend is faster and + supports LZF compression to speed it up further. -- cgit v1.2.3