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
2024-01-29 09:16:02 -08:00
2022-12-22 11:34:28 -08:00
2020-06-09 21:24:09 -07:00
2018-05-29 16:00:33 -07:00
2024-04-17 09:29:21 -07:00
2020-08-26 21:44:41 -07:00
2018-05-29 16:00:33 -07:00
2023-11-27 12:58:03 -08:00
2021-04-02 16:33:40 -07:00
2020-03-16 10:46:03 -07:00

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OpenZFS is an advanced file system and volume manager which was originally developed for Solaris and is now maintained by the OpenZFS community. This repository contains the code for running OpenZFS on Linux and FreeBSD.

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Official Resources

Installation

Full documentation for installing OpenZFS on your favorite operating system can be found at the Getting Started Page.

Contribute & Develop

We have a separate document with contribution guidelines.

We have a Code of Conduct.

Release

OpenZFS is released under a CDDL license. For more details see the NOTICE, LICENSE and COPYRIGHT files; UCRL-CODE-235197

Supported Kernels

  • The META file contains the officially recognized supported Linux kernel versions.
  • Supported FreeBSD versions are any supported branches and releases starting from 12.4-RELEASE.
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