AuxXxilium/linux_dsm_epyc7002
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76a5e75cb8
linux_dsm_epyc7002/fs
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Linus Torvalds 76a5e75cb8 pipe: avoid unnecessary EPOLLET wakeups under normal loads 
commit 3b844826b6c6affa80755254da322b017358a2f4 upstream.

I had forgotten just how sensitive hackbench is to extra pipe wakeups,
and commit 3a34b13a88ca ("pipe: make pipe writes always wake up
readers") ended up causing a quite noticeable regression on larger
machines.

Now, hackbench isn't necessarily a hugely meaningful benchmark, and it's
not clear that this matters in real life all that much, but as Mel
points out, it's used often enough when comparing kernels and so the
performance regression shows up like a sore thumb.

It's easy enough to fix at least for the common cases where pipes are
used purely for data transfer, and you never have any exciting poll
usage at all.  So set a special 'poll_usage' flag when there is polling
activity, and make the ugly "EPOLLET has crazy legacy expectations"
semantics explicit to only that case.

I would love to limit it to just the broken EPOLLET case, but the pipe
code can't see the difference between epoll and regular select/poll, so
any non-read/write waiting will trigger the extra wakeup behavior.  That
is sufficient for at least the hackbench case.

Apart from making the odd extra wakeup cases more explicitly about
EPOLLET, this also makes the extra wakeup be at the _end_ of the pipe
write, not at the first write chunk.  That is actually much saner
semantics (as much as you can call any of the legacy edge-triggered
expectations for EPOLLET "sane") since it means that you know the wakeup
will happen once the write is done, rather than possibly in the middle
of one.

[ For stable people: I'm putting a "Fixes" tag on this, but I leave it
  up to you to decide whether you actually want to backport it or not.
  It likely has no impact outside of synthetic benchmarks  - Linus ]

Link: https://lore.kernel.org/lkml/20210802024945.GA8372@xsang-OptiPlex-9020/
Fixes: 3a34b13a88ca ("pipe: make pipe writes always wake up readers")
Reported-by: kernel test robot <oliver.sang@intel.com>
Tested-by: Sandeep Patil <sspatil@android.com>
Tested-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-07-05 19:00:50 +02:00
..
9p fs: 9p: add generic splice_write file operation 2020-12-01 21:40:47 +01:00
adfs Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-24 12:26:05 -07:00
affs fs/affs: release old buffer head on error path 2021-03-04 11:38:37 +01:00
afs afs: Fix tracepoint string placement with built-in AFS 2021-07-28 14:35:41 +02:00
aufs init: add dsm gpl source 2024-07-05 18:00:04 +02:00
autofs autofs: harden ioctl table 2020-10-16 11:11:22 -07:00
befs [PATCH] reduce boilerplate in fsid handling 2020-09-18 16:45:50 -04:00
bfs bfs: don't use WARNING: string when it's just info. 2021-01-06 14:56:52 +01:00
btrfs btrfs: fix race between marking inode needs to be logged and log syncing 2024-07-05 19:00:50 +02:00
cachefiles fs/cachefiles: Remove wait_bit_key layout dependency 2021-03-30 14:32:07 +02:00
ceph init: add dsm gpl source 2024-07-05 18:00:04 +02:00
cifs cifs: create sd context must be a multiple of 8 2024-07-05 18:53:59 +02:00
coda
configfs init: add dsm gpl source 2024-07-05 18:00:04 +02:00
cramfs [PATCH] reduce boilerplate in fsid handling 2020-09-18 16:45:50 -04:00
crypto fscrypt: fix derivation of SipHash keys on big endian CPUs 2021-07-14 16:56:53 +02:00
debugfs init: add dsm gpl source 2024-07-05 18:00:04 +02:00
devpts
dlm fs: dlm: fix memory leak when fenced 2021-07-14 16:55:59 +02:00
ecryptfs init: add dsm gpl source 2024-07-05 18:00:04 +02:00
efivarfs efivarfs: revert "fix memory leak in efivarfs_create()" 2020-11-25 16:55:02 +01:00
efs [PATCH] reduce boilerplate in fsid handling 2020-09-18 16:45:50 -04:00
erofs erofs: fix error return code in erofs_read_superblock() 2021-07-14 16:56:53 +02:00
exfat init: add dsm gpl source 2024-07-05 18:00:04 +02:00
exportfs init: add dsm gpl source 2024-07-05 18:00:04 +02:00
ext2 Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-24 12:26:05 -07:00
ext4 ext4: fix potential htree corruption when growing large_dir directories 2024-07-05 18:52:29 +02:00
f2fs f2fs: Show casefolding support only when supported 2021-07-25 14:36:17 +02:00
fat init: add dsm gpl source 2024-07-05 18:00:04 +02:00
freevxfs
fscache
fuse init: add dsm gpl source 2024-07-05 18:00:04 +02:00
gfs2 gfs2: Fix error handling in init_statfs 2021-07-14 16:55:38 +02:00
hfs hfs: add lock nesting notation to hfs_find_init 2021-07-31 08:16:12 +02:00
hfsplus init: add dsm gpl source 2024-07-05 18:00:04 +02:00
hostfs hostfs: fix memory handling in follow_link() 2021-04-14 08:42:06 +02:00
hpfs [PATCH] reduce boilerplate in fsid handling 2020-09-18 16:45:50 -04:00
hugetlbfs hugetlbfs: fix mount mode command line processing 2021-07-28 14:35:46 +02:00
iomap init: add dsm gpl source 2024-07-05 18:00:04 +02:00
isofs init: add dsm gpl source 2024-07-05 18:00:04 +02:00
jbd2 ext4: fix debug format string warning 2021-05-19 10:13:19 +02:00
jffs2 jffs2: check the validity of dstlen in jffs2_zlib_compress() 2021-05-11 14:47:36 +02:00
jfs fs/jfs: Fix missing error code in lmLogInit() 2021-07-20 16:05:40 +02:00
kernfs kernfs: wire up ->splice_read and ->splice_write 2021-01-27 11:55:29 +01:00
lockd init: add dsm gpl source 2024-07-05 18:00:04 +02:00
minix [PATCH] reduce boilerplate in fsid handling 2020-09-18 16:45:50 -04:00
nfs init: add dsm gpl source 2024-07-05 18:00:04 +02:00
nfs_common nfs_common: need lock during iterate through the list 2020-12-30 11:53:45 +01:00
nfsd init: add dsm gpl source 2024-07-05 18:00:04 +02:00
nilfs2 nilfs2: fix memory leak in nilfs_sysfs_delete_device_group 2021-06-30 08:47:24 -04:00
nls
notify init: add dsm gpl source 2024-07-05 18:00:04 +02:00
ntfs ntfs: fix validity check for file name attribute 2021-07-14 16:55:38 +02:00
ocfs2 ocfs2: issue zeroout to EOF blocks 2024-07-05 18:03:15 +02:00
omfs fs: omfs: use kmemdup() rather than kmalloc+memcpy 2020-09-22 23:39:45 -04:00
openpromfs
orangefs orangefs: fix orangefs df output. 2021-07-20 16:05:48 +02:00
overlayfs ovl: fix uninitialized pointer read in ovl_lookup_real_one() 2024-07-05 18:56:55 +02:00
proc init: add dsm gpl source 2024-07-05 18:00:04 +02:00
pstore init: add dsm gpl source 2024-07-05 18:00:04 +02:00
qnx4 [PATCH] reduce boilerplate in fsid handling 2020-09-18 16:45:50 -04:00
qnx6 [PATCH] reduce boilerplate in fsid handling 2020-09-18 16:45:50 -04:00
quota init: add dsm gpl source 2024-07-05 18:00:04 +02:00
ramfs ramfs: fix nommu mmap with gaps in the page cache 2020-10-16 11:11:22 -07:00
reiserfs reiserfs: check directory items on read from disk 2024-07-05 18:52:32 +02:00
romfs Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-24 12:26:05 -07:00
squashfs squashfs: fix divide error in calculate_skip() 2021-05-19 10:13:10 +02:00
sysfs sysfs: Add sysfs_emit and sysfs_emit_at to format sysfs output 2020-10-02 12:02:30 +02:00
sysv [PATCH] reduce boilerplate in fsid handling 2020-09-18 16:45:50 -04:00
tracefs
ubifs ubifs: Set/Clear I_LINKABLE under i_lock for whiteout inode 2021-07-20 16:05:51 +02:00
udf init: add dsm gpl source 2024-07-05 18:00:04 +02:00
ufs Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-10-24 12:26:05 -07:00
unicode unicode: Add utf8_casefold_hash 2020-09-10 14:03:31 -07:00
vboxsf vboxsf: Add support for the atomic_open directory-inode op 2024-07-05 18:54:41 +02:00
verity fs-verity: use smp_load_acquire() for ->i_verity_info 2020-07-21 16:02:41 -07:00
xfs xfs: fix return of uninitialized value in variable error 2021-05-14 09:50:34 +02:00
zonefs zonefs: fix to update .i_wr_refcnt correctly in zonefs_open_zone() 2021-03-25 09:04:05 +01:00
aio.c init: add dsm gpl source 2024-07-05 18:00:04 +02:00
anon_inodes.c
attr.c init: add dsm gpl source 2024-07-05 18:00:04 +02:00
bad_inode.c
binfmt_aout.c
binfmt_elf_fdpic.c binfmt_elf, binfmt_elf_fdpic: use a VMA list snapshot 2020-10-16 11:11:21 -07:00
binfmt_elf.c fs: Replace zero-length array with flexible-array member 2020-10-29 17:22:59 -05:00
binfmt_em86.c
binfmt_flat.c binfmt_flat: revert "binfmt_flat: don't offset the data start" 2020-08-24 08:49:13 +10:00
binfmt_misc.c binfmt_misc: fix possible deadlock in bm_register_write 2021-03-17 17:06:35 +01:00
binfmt_script.c
block_dev.c block: fix a race between del_gendisk and BLKRRPART 2021-06-03 09:00:45 +02:00
buffer.c init: add dsm gpl source 2024-07-05 18:00:04 +02:00
char_dev.c
compat_binfmt_elf.c
coredump.c coredump: fix core_pattern parse error 2020-12-06 10:19:07 -08:00
d_path.c fs: fix NULL dereference due to data race in prepend_path() 2020-10-14 14:54:45 -07:00
dax.c dax: fix ENOMEM handling in grab_mapping_entry() 2021-07-14 16:56:13 +02:00
dcache.c init: add dsm gpl source 2024-07-05 18:00:04 +02:00
dcookies.c
direct-io.c fs: direct-io: fix missing sdio->boundary 2021-04-14 08:41:58 +02:00
drop_caches.c
eventfd.c
eventpoll.c fs/epoll: restore waking from ep_done_scan() 2021-05-11 14:47:12 +02:00
exec.c init: add dsm gpl source 2024-07-05 18:00:04 +02:00
fcntl.c init: add dsm gpl source 2024-07-05 18:00:04 +02:00
fhandle.c
file_table.c init: add dsm gpl source 2024-07-05 18:00:04 +02:00
file.c kernel/io_uring: cancel io_uring before task works 2021-01-30 13:55:18 +01:00
filesystems.c
fs_context.c init: add dsm gpl source 2024-07-05 18:00:04 +02:00
fs_parser.c fs_parse: mark fs_param_bad_value() as static 2020-10-13 18:38:27 -07:00
fs_pin.c
fs_struct.c vfs: Use sequence counter with associated spinlock 2020-07-29 16:14:27 +02:00
fs_types.c
fs-writeback.c init: add dsm gpl source 2024-07-05 18:00:04 +02:00
fsopen.c treewide: Use fallthrough pseudo-keyword 2020-08-23 17:36:59 -05:00
init.c init: add an init_dup helper 2020-08-04 21:02:38 -04:00
inode.c init: add dsm gpl source 2024-07-05 18:00:04 +02:00
internal.h init: add dsm gpl source 2024-07-05 18:00:04 +02:00
io_uring.c io_uring: only assign io_uring_enter() SQPOLL error in actual error case 2024-07-05 18:56:00 +02:00
io-wq.c io_uring: fix false WARN_ONCE 2021-07-19 09:44:51 +02:00
io-wq.h io_uring: always batch cancel in *cancel_files() 2021-02-13 13:54:56 +01:00
ioctl.c init: add dsm gpl source 2024-07-05 18:00:04 +02:00
Kconfig init: add dsm gpl source 2024-07-05 18:00:04 +02:00
Kconfig.binfmt
kernel_read_file.c fs/kernel_file_read: Add "offset" arg for partial reads 2020-10-05 13:37:04 +02:00
libfs.c libfs: fix error cast of negative value in simple_attr_write() 2020-11-22 10:48:22 -08:00
locks.c Revert "nfsd4: a client's own opens needn't prevent delegations" 2021-03-20 10:43:44 +01:00
Makefile init: add dsm gpl source 2024-07-05 18:00:04 +02:00
mbcache.c
mount.h init: add dsm gpl source 2024-07-05 18:00:04 +02:00
mpage.c
namei.c init: add dsm gpl source 2024-07-05 18:00:04 +02:00
namespace.c fs: warn about impending deprecation of mandatory locks 2024-07-05 18:56:00 +02:00
no-block.c
nsfs.c
open.c init: add dsm gpl source 2024-07-05 18:00:04 +02:00
pipe.c pipe: avoid unnecessary EPOLLET wakeups under normal loads 2024-07-05 19:00:50 +02:00
pnode.c
pnode.h mount: fix mounting of detached mounts onto targets that reside on shared mounts 2021-03-17 17:06:13 +01:00
posix_acl.c
proc_namespace.c init: add dsm gpl source 2024-07-05 18:00:04 +02:00
read_write.c init: add dsm gpl source 2024-07-05 18:00:04 +02:00
readdir.c readdir: make sure to verify directory entry for legacy interfaces too 2021-04-21 13:00:54 +02:00
remap_range.c init: add dsm gpl source 2024-07-05 18:00:04 +02:00
select.c kernel, fs: Introduce and use set_restart_fn() and arch_set_restart_data() 2021-03-25 09:04:16 +01:00
seq_file.c seq_file: disallow extremely large seq buffer allocations 2021-07-20 16:05:59 +02:00
signalfd.c init: add dsm gpl source 2024-07-05 18:00:04 +02:00
splice.c init: add dsm gpl source 2024-07-05 18:00:04 +02:00
stack.c init: add dsm gpl source 2024-07-05 18:00:04 +02:00
stat.c init: add dsm gpl source 2024-07-05 18:00:04 +02:00
statfs.c Add a "nosymfollow" mount option. 2020-08-27 16:06:47 -04:00
super.c init: add dsm gpl source 2024-07-05 18:00:04 +02:00
sync.c init: add dsm gpl source 2024-07-05 18:00:04 +02:00
syno_acl_api.c init: add dsm gpl source 2024-07-05 18:00:04 +02:00
syno_acl.c init: add dsm gpl source 2024-07-05 18:00:04 +02:00
syno_acl.h init: add dsm gpl source 2024-07-05 18:00:04 +02:00
timerfd.c
userfaultfd.c userfaultfd: do not untag user pointers 2021-07-28 14:35:46 +02:00
utimes.c init: add dsm gpl source 2024-07-05 18:00:04 +02:00
xattr.c init: add dsm gpl source 2024-07-05 18:00:04 +02:00