https://github.com/torvalds/linux
Revision e0c274472d5d27f277af722e017525e0b33784cd authored by Johannes Weiner on 30 November 2018, 22:09:58 UTC, committed by Linus Torvalds on 30 November 2018, 22:56:14 UTC
Mel Gorman reports a hackbench regression with psi that would prohibit shipping the suse kernel with it default-enabled, but he'd still like users to be able to opt in at little to no cost to others. With the current combination of CONFIG_PSI and the psi_disabled bool set from the commandline, this is a challenge. Do the following things to make it easier: 1. Add a config option CONFIG_PSI_DEFAULT_DISABLED that allows distros to enable CONFIG_PSI in their kernel but leave the feature disabled unless a user requests it at boot-time. To avoid double negatives, rename psi_disabled= to psi=. 2. Make psi_disabled a static branch to eliminate any branch costs when the feature is disabled. In terms of numbers before and after this patch, Mel says: : The following is a comparision using CONFIG_PSI=n as a baseline against : your patch and a vanilla kernel : : 4.20.0-rc4 4.20.0-rc4 4.20.0-rc4 : kconfigdisable-v1r1 vanilla psidisable-v1r1 : Amean 1 1.3100 ( 0.00%) 1.3923 ( -6.28%) 1.3427 ( -2.49%) : Amean 3 3.8860 ( 0.00%) 4.1230 * -6.10%* 3.8860 ( -0.00%) : Amean 5 6.8847 ( 0.00%) 8.0390 * -16.77%* 6.7727 ( 1.63%) : Amean 7 9.9310 ( 0.00%) 10.8367 * -9.12%* 9.9910 ( -0.60%) : Amean 12 16.6577 ( 0.00%) 18.2363 * -9.48%* 17.1083 ( -2.71%) : Amean 18 26.5133 ( 0.00%) 27.8833 * -5.17%* 25.7663 ( 2.82%) : Amean 24 34.3003 ( 0.00%) 34.6830 ( -1.12%) 32.0450 ( 6.58%) : Amean 30 40.0063 ( 0.00%) 40.5800 ( -1.43%) 41.5087 ( -3.76%) : Amean 32 40.1407 ( 0.00%) 41.2273 ( -2.71%) 39.9417 ( 0.50%) : : It's showing that the vanilla kernel takes a hit (as the bisection : indicated it would) and that disabling PSI by default is reasonably : close in terms of performance for this particular workload on this : particular machine so; Link: http://lkml.kernel.org/r/20181127165329.GA29728@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Tested-by: Mel Gorman <mgorman@techsingularity.net> Reported-by: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Tip revision: e0c274472d5d27f277af722e017525e0b33784cd authored by Johannes Weiner on 30 November 2018, 22:09:58 UTC
psi: make disabling/enabling easier for vendor kernels
psi: make disabling/enabling easier for vendor kernels
Tip revision: e0c2744
File | Mode | Size |
---|---|---|
partitions | ||
Kconfig | -rw-r--r-- | 6.7 KB |
Kconfig.iosched | -rw-r--r-- | 2.7 KB |
Makefile | -rw-r--r-- | 1.6 KB |
badblocks.c | -rw-r--r-- | 14.5 KB |
bfq-cgroup.c | -rw-r--r-- | 33.5 KB |
bfq-iosched.c | -rw-r--r-- | 191.6 KB |
bfq-iosched.h | -rw-r--r-- | 32.3 KB |
bfq-wf2q.c | -rw-r--r-- | 52.2 KB |
bio-integrity.c | -rw-r--r-- | 12.9 KB |
bio.c | -rw-r--r-- | 51.3 KB |
blk-cgroup.c | -rw-r--r-- | 47.5 KB |
blk-core.c | -rw-r--r-- | 98.7 KB |
blk-exec.c | -rw-r--r-- | 2.9 KB |
blk-flush.c | -rw-r--r-- | 17.3 KB |
blk-integrity.c | -rw-r--r-- | 12.0 KB |
blk-ioc.c | -rw-r--r-- | 10.9 KB |
blk-iolatency.c | -rw-r--r-- | 28.3 KB |
blk-lib.c | -rw-r--r-- | 10.2 KB |
blk-map.c | -rw-r--r-- | 5.9 KB |
blk-merge.c | -rw-r--r-- | 22.8 KB |
blk-mq-cpumap.c | -rw-r--r-- | 1.6 KB |
blk-mq-debugfs-zoned.c | -rw-r--r-- | 478 bytes |
blk-mq-debugfs.c | -rw-r--r-- | 24.2 KB |
blk-mq-debugfs.h | -rw-r--r-- | 2.3 KB |
blk-mq-pci.c | -rw-r--r-- | 1.7 KB |
blk-mq-rdma.c | -rw-r--r-- | 1.7 KB |
blk-mq-sched.c | -rw-r--r-- | 13.0 KB |
blk-mq-sched.h | -rw-r--r-- | 2.6 KB |
blk-mq-sysfs.c | -rw-r--r-- | 8.1 KB |
blk-mq-tag.c | -rw-r--r-- | 14.4 KB |
blk-mq-tag.h | -rw-r--r-- | 2.3 KB |
blk-mq-virtio.c | -rw-r--r-- | 1.7 KB |
blk-mq.c | -rw-r--r-- | 79.5 KB |
blk-mq.h | -rw-r--r-- | 5.8 KB |
blk-pm.c | -rw-r--r-- | 6.6 KB |
blk-pm.h | -rw-r--r-- | 1.4 KB |
blk-rq-qos.c | -rw-r--r-- | 4.1 KB |
blk-rq-qos.h | -rw-r--r-- | 2.6 KB |
blk-settings.c | -rw-r--r-- | 28.6 KB |
blk-softirq.c | -rw-r--r-- | 4.5 KB |
blk-stat.c | -rw-r--r-- | 4.8 KB |
blk-stat.h | -rw-r--r-- | 4.5 KB |
blk-sysfs.c | -rw-r--r-- | 25.1 KB |
blk-tag.c | -rw-r--r-- | 9.3 KB |
blk-throttle.c | -rw-r--r-- | 68.4 KB |
blk-timeout.c | -rw-r--r-- | 6.0 KB |
blk-wbt.c | -rw-r--r-- | 19.0 KB |
blk-wbt.h | -rw-r--r-- | 3.0 KB |
blk-zoned.c | -rw-r--r-- | 11.7 KB |
blk.h | -rw-r--r-- | 15.0 KB |
bounce.c | -rw-r--r-- | 9.1 KB |
bsg-lib.c | -rw-r--r-- | 8.7 KB |
bsg.c | -rw-r--r-- | 12.4 KB |
cfq-iosched.c | -rw-r--r-- | 126.8 KB |
cmdline-parser.c | -rw-r--r-- | 4.9 KB |
compat_ioctl.c | -rw-r--r-- | 10.9 KB |
deadline-iosched.c | -rw-r--r-- | 13.2 KB |
elevator.c | -rw-r--r-- | 26.9 KB |
genhd.c | -rw-r--r-- | 49.3 KB |
ioctl.c | -rw-r--r-- | 15.3 KB |
ioprio.c | -rw-r--r-- | 5.1 KB |
kyber-iosched.c | -rw-r--r-- | 28.2 KB |
mq-deadline.c | -rw-r--r-- | 20.0 KB |
noop-iosched.c | -rw-r--r-- | 2.6 KB |
opal_proto.h | -rw-r--r-- | 9.3 KB |
partition-generic.c | -rw-r--r-- | 17.2 KB |
scsi_ioctl.c | -rw-r--r-- | 19.1 KB |
sed-opal.c | -rw-r--r-- | 58.8 KB |
t10-pi.c | -rw-r--r-- | 7.9 KB |
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