From: "brian m. carlson" <sandals@crustytoothpaste.net>
To: Johannes Sixt <j6t@kdbg.org>
Cc: Patrick Steinhardt <ps@pks.im>, Jeff King <peff@peff.net>,
Junio C Hamano <gitster@pobox.com>,
Matt Smiley <msmiley@gitlab.com>,
git@vger.kernel.org
Subject: Re: [PATCH v2 05/10] compat/posix: introduce writev(3p) wrapper
Date: Thu, 5 Mar 2026 22:22:45 +0000 [thread overview]
Message-ID: <aaoCNUY3XVyFaDcu@fruit.crustytoothpaste.net> (raw)
In-Reply-To: <7e8b51d1-382d-47f8-be71-74e76f0c9888@kdbg.org>
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On 2026-03-05 at 06:39:13, Johannes Sixt wrote:
> Please don't. The use of writev may mislead you to depend on guarantees
> that a kernel implementation of writev can provide, but a compat/
> implementation cannot. (For example, I read something about "the file
> pointer shall be unchanged" in the case of errors.) Please use simple
> and stupid functions (write). I highly doubt that you can squeeze out a
> noticable performance improvement with writev.
I have Rust code that does show a substantial performance improvement
with writev and I use it for a very similar purpose (printing the size
before a packet of data).
I am okay with slightly loosening the guarantees to support our compat
implementation if that's what we need to do.
--
brian m. carlson (they/them)
Toronto, Ontario, CA
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next prev parent reply other threads:[~2026-03-05 22:22 UTC|newest]
Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-27 11:22 [PATCH 0/2] upload-pack: reduce lock contention when writing packfile data Patrick Steinhardt
2026-02-27 11:23 ` [PATCH 1/2] upload-pack: fix debug statement when flushing " Patrick Steinhardt
2026-02-27 11:23 ` [PATCH 2/2] upload-pack: reduce lock contention when writing " Patrick Steinhardt
2026-02-27 13:04 ` brian m. carlson
2026-02-27 18:14 ` Patrick Steinhardt
2026-02-27 17:29 ` Junio C Hamano
2026-02-27 19:37 ` Jeff King
2026-03-02 12:12 ` Patrick Steinhardt
2026-03-02 18:20 ` Jeff King
2026-03-03 9:31 ` Patrick Steinhardt
2026-03-03 13:35 ` Jeff King
2026-03-03 13:47 ` Patrick Steinhardt
2026-03-03 15:00 ` [PATCH v2 00/10] " Patrick Steinhardt
2026-03-03 15:00 ` [PATCH v2 01/10] upload-pack: fix debug statement when flushing " Patrick Steinhardt
2026-03-03 15:00 ` [PATCH v2 02/10] upload-pack: adapt keepalives based on buffering Patrick Steinhardt
2026-03-05 0:56 ` Jeff King
2026-03-10 12:08 ` Patrick Steinhardt
2026-03-03 15:00 ` [PATCH v2 03/10] upload-pack: reduce lock contention when writing packfile data Patrick Steinhardt
2026-03-05 1:16 ` Jeff King
2026-03-10 12:14 ` Patrick Steinhardt
2026-03-03 15:00 ` [PATCH v2 04/10] git-compat-util: introduce `cast_size_t_to_ssize_t()` Patrick Steinhardt
2026-03-03 15:00 ` [PATCH v2 05/10] compat/posix: introduce writev(3p) wrapper Patrick Steinhardt
2026-03-04 22:01 ` Junio C Hamano
2026-03-05 0:37 ` Jeff King
2026-03-05 2:16 ` brian m. carlson
2026-03-05 6:39 ` Johannes Sixt
2026-03-05 22:22 ` brian m. carlson [this message]
2026-03-10 12:09 ` Patrick Steinhardt
2026-03-03 15:00 ` [PATCH v2 06/10] wrapper: introduce writev(3p) wrappers Patrick Steinhardt
2026-03-03 15:00 ` [PATCH v2 07/10] sideband: use writev(3p) to send pktlines Patrick Steinhardt
2026-03-04 22:05 ` Junio C Hamano
2026-03-03 15:00 ` [PATCH v2 08/10] csum-file: introduce `hashfd_ext()` Patrick Steinhardt
2026-03-04 22:11 ` Junio C Hamano
2026-03-10 12:09 ` Patrick Steinhardt
2026-03-03 15:00 ` [PATCH v2 09/10] csum-file: drop `hashfd_throughput()` Patrick Steinhardt
2026-03-03 15:00 ` [PATCH v2 10/10] builtin/pack-objects: reduce lock contention when writing packfile data Patrick Steinhardt
2026-03-10 13:24 ` [PATCH v3 00/10] upload-pack: " Patrick Steinhardt
2026-03-10 13:24 ` [PATCH v3 01/10] upload-pack: fix debug statement when flushing " Patrick Steinhardt
2026-03-10 13:24 ` [PATCH v3 02/10] upload-pack: adapt keepalives based on buffering Patrick Steinhardt
2026-03-10 13:24 ` [PATCH v3 03/10] upload-pack: prefer flushing data over sending keepalive Patrick Steinhardt
2026-03-10 17:09 ` Junio C Hamano
2026-03-10 17:43 ` Patrick Steinhardt
2026-03-10 13:25 ` [PATCH v3 04/10] upload-pack: reduce lock contention when writing packfile data Patrick Steinhardt
2026-03-10 13:25 ` [PATCH v3 05/10] compat/posix: introduce writev(3p) wrapper Patrick Steinhardt
2026-03-10 16:59 ` Junio C Hamano
2026-03-10 13:25 ` [PATCH v3 06/10] wrapper: introduce writev(3p) wrappers Patrick Steinhardt
2026-03-10 13:25 ` [PATCH v3 07/10] sideband: use writev(3p) to send pktlines Patrick Steinhardt
2026-03-10 13:25 ` [PATCH v3 08/10] csum-file: introduce `hashfd_ext()` Patrick Steinhardt
2026-03-10 13:25 ` [PATCH v3 09/10] csum-file: drop `hashfd_throughput()` Patrick Steinhardt
2026-03-10 13:25 ` [PATCH v3 10/10] builtin/pack-objects: reduce lock contention when writing packfile data Patrick Steinhardt
2026-03-10 17:11 ` [PATCH v3 00/10] upload-pack: " Junio C Hamano
2026-03-10 20:56 ` Johannes Sixt
2026-03-11 6:27 ` Patrick Steinhardt
2026-03-13 6:45 ` [PATCH v4 " Patrick Steinhardt
2026-03-13 6:45 ` [PATCH v4 01/10] upload-pack: fix debug statement when flushing " Patrick Steinhardt
2026-03-13 6:45 ` [PATCH v4 02/10] upload-pack: adapt keepalives based on buffering Patrick Steinhardt
2026-03-13 6:45 ` [PATCH v4 03/10] upload-pack: prefer flushing data over sending keepalive Patrick Steinhardt
2026-03-13 6:45 ` [PATCH v4 04/10] upload-pack: reduce lock contention when writing packfile data Patrick Steinhardt
2026-03-13 6:45 ` [PATCH v4 05/10] compat/posix: introduce writev(3p) wrapper Patrick Steinhardt
2026-03-13 6:45 ` [PATCH v4 06/10] wrapper: introduce writev(3p) wrappers Patrick Steinhardt
2026-03-13 6:45 ` [PATCH v4 07/10] sideband: use writev(3p) to send pktlines Patrick Steinhardt
2026-03-13 6:45 ` [PATCH v4 08/10] csum-file: introduce `hashfd_ext()` Patrick Steinhardt
2026-03-13 6:45 ` [PATCH v4 09/10] csum-file: drop `hashfd_throughput()` Patrick Steinhardt
2026-03-13 6:45 ` [PATCH v4 10/10] builtin/pack-objects: reduce lock contention when writing packfile data Patrick Steinhardt
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