From: Jacob Vosmaer <jacob@gitlab.com>
To: Jeff King <peff@peff.net>
Cc: git@vger.kernel.org
Subject: Re: [PATCH 1/1] upload-pack.c: make output buffer size configurable
Date: Tue, 14 Dec 2021 21:04:49 +0100 [thread overview]
Message-ID: <CADMWQoOaPQaCQa5V+1Dujc6A=+f8rnv7MG+fP1mZi1kwm=d3fQ@mail.gmail.com> (raw)
In-Reply-To: <Ybi6SwndUHLs27bO@coredump.intra.peff.net>
On Tue, Dec 14, 2021 at 4:37 PM Jeff King <peff@peff.net> wrote:
>
> It gets about 2.3GB/s with the tip of 'master' and 3.2GB/s with the
> equivalent of your patch (using LARGE_PACKET_DATA_MAX). So definitely an
> improvement.
>
> Without the cached case (so actually running pack-objects, albeit a
> pretty quick one because of bitmaps and pack-reuse), the timings are
> about the same (171MB/s versus 174MB/s, but really it's just pegging a
> CPU running pack-objects). So it would be fine to just do this
> unconditionally, I think.
Thank you for validating this!
> Looking at strace, the other thing I notice is that we write() the
> packet header separately in send_sideband(), which doubles the number of
> syscalls. I hackily re-wrote this to use writev() instead (patch below),
> but it doesn't seem to actually help much (maybe a curiosity to explore
> further, but definitely not something to hold up your patch).
Those double writes bug me too. Getting rid of them was one of the
things I liked about using stdio here. Curious now if writev will make
an impact in my benchmarks. As your experiments indicate, the double
writes may not be a problem in real life. Either way, I also feel it
is not something to rope into this patch set.
next prev parent reply other threads:[~2021-12-14 20:05 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-13 13:23 [PATCH 0/1] Make upload-pack pack write size configurable Jacob Vosmaer
2021-12-13 13:23 ` [PATCH 1/1] upload-pack.c: make output buffer " Jacob Vosmaer
2021-12-14 12:08 ` Ævar Arnfjörð Bjarmason
2021-12-14 15:08 ` Jeff King
2021-12-14 19:46 ` [PATCH v2 0/1] upload-pack.c: increase output buffer size Jacob Vosmaer
2021-12-14 19:46 ` [PATCH v2 1/1] " Jacob Vosmaer
2021-12-14 20:41 ` Ævar Arnfjörð Bjarmason
2021-12-15 16:30 ` Jeff King
2021-12-15 19:50 ` Junio C Hamano
2021-12-15 19:59 ` rsbecker
2021-12-15 20:24 ` Jacob Vosmaer
2021-12-15 20:38 ` rsbecker
2021-12-15 20:45 ` Jacob Vosmaer
2021-12-15 21:34 ` rsbecker
2021-12-14 15:37 ` [PATCH 1/1] upload-pack.c: make output buffer size configurable Jeff King
2021-12-14 20:04 ` Jacob Vosmaer [this message]
2021-12-14 15:12 ` [PATCH 0/1] Make upload-pack pack write " Jeff King
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