mirror_zfs/module
Mateusz Guzik a7fc4c85e3
zstd: don't call zstd_mempool_reap if there are no buffers (#16302)
zfs_zstd_cache_reap_now is issued every second.

zstd_mempool_reap checks for both pool existence and buffer count, but
that's still 2 func calls which are trivially avoidable.

With clang it even avoids pushing the stack pointer (but still suffers
the mispredict due to a forward jump, not modified in case someone is
using zstd):

<+0>:     cmpq   $0x0,0x0(%rip)        # <zfs_zstd_cache_reap_now+8>
<+8>:     je     0x217de4 <zfs_zstd_cache_reap_now+36>
<+10>:    push   %rbp
<+11>:    mov    %rsp,%rbp
<+14>:    mov    0x0(%rip),%rdi        # <zfs_zstd_cache_reap_now+21>
<+21>:    call   0x217df0 <zstd_mempool_reap>
<+26>:    mov    0x0(%rip),%rdi        # <zfs_zstd_cache_reap_now+33>
<+33>:    pop    %rbp
<+34>:    jmp    0x217df0 <zstd_mempool_reap>
<+36>:    ret

Preferably the call would not be made to begin with if zstd is not used,
but this retains all the logic confined to zstd code.

Sponsored by:	Rubicon Communications, LLC ("Netgate")
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Reviewed-by: Allan Jude <allan@klarasystems.com>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
2024-07-15 14:51:37 -07:00
..
avl Suppress Clang Static Analyzer false positive in the AVL tree code. 2023-03-08 13:51:21 -08:00
icp icp: remove redundant FreeBSD check 2024-05-31 15:13:59 -07:00
lua LUA: Backport CVE-2020-24370's patch 2024-02-07 11:53:05 -08:00
nvpair xdr: header cleanup 2024-04-03 15:13:27 -07:00
os FreeBSD: Use the new freeuio() helper to free dynamically allocated UIOs (#16300) 2024-07-11 16:52:51 -07:00
unicode Illumos #15286: do_composition() needs sign awareness 2023-01-05 11:16:21 -08:00
zcommon Replace P2ALIGN with P2ALIGN_TYPED and delete P2ALIGN. 2024-05-10 08:47:21 -07:00
zfs head_errlog: fix use-after-free 2024-07-15 09:05:42 -07:00
zstd zstd: don't call zstd_mempool_reap if there are no buffers (#16302) 2024-07-15 14:51:37 -07:00
.gitignore FreeBSD: Ignore symlink to i386 includes 2022-08-02 16:34:23 -07:00
Kbuild.in Linux 6.9: Fix UBSAN errors in zap_micro.c 2024-07-11 16:41:26 -07:00
Makefile.bsd Makefile.bsd: sort and cleanup source file list 2024-04-03 15:49:22 -07:00
Makefile.in check-zstd-symbols: also ignore __pfx_ symbols 2023-09-18 09:08:41 -07:00