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From:   Junio C Hamano <gitster@pobox.com>
To:     Jeff King <peff@peff.net>
Cc:     Jeff Hostetler via GitGitGadget <gitgitgadget@gmail.com>,
        git@vger.kernel.org,
        =?utf-8?B?w4Z2YXIgQXJuZmrDtnLDsA==?= Bjarmason <avarab@gmail.com>,
        Jeff Hostetler <git@jeffhostetler.com>,
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        Johannes Schindelin <Johannes.Schindelin@gmx.de>,
        Chris Torek <chris.torek@gmail.com>,
        Jeff Hostetler <jeffhost@microsoft.com>
Subject: Re: [PATCH v5 01/12] pkt-line: eliminate the need for static buffer
 in packet_write_gently()
References: <pull.766.v4.git.1613598529.gitgitgadget@gmail.com>
        <pull.766.v5.git.1615302157.gitgitgadget@gmail.com>
        <311ea4a5cd71c5dd2407348ad4608d2f7dd77ce5.1615302157.git.gitgitgadget@gmail.com>
        <xmqqblbrzy5j.fsf@gitster.c.googlers.com>
        <YEpvfztZWhAvSDTL@coredump.intra.peff.net>
Date:   Thu, 11 Mar 2021 12:32:29 -0800
In-Reply-To: <YEpvfztZWhAvSDTL@coredump.intra.peff.net> (Jeff King's message
        of "Thu, 11 Mar 2021 14:29:03 -0500")
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Jeff King <peff@peff.net> writes:

> On Tue, Mar 09, 2021 at 03:48:40PM -0800, Junio C Hamano wrote:
>
>> "Jeff Hostetler via GitGitGadget" <gitgitgadget@gmail.com> writes:
>> 
>> > +	/*
>> > +	 * Write the header and the buffer in 2 parts so that we do not need
>> > +	 * to allocate a buffer or rely on a static buffer.  This avoids perf
>> > +	 * and multi-threading issues.
>> > +	 */
>> 
>> I understand "multi-threading issues" (i.e. let's not have too much
>> stuff on the stack), but what issue around "perf" are we worried
>> about?
>>  ...
> Yeah, this came from my suggestion. My gut feeling is that it isn't
> likely to matter, but I'd much rather solve any performance problem we
> find using writev(), which would be pretty easy to emulate with a
> wrapper for systems that lack it.

I too had writev() in mind when I said "can fix it locally", so we
are on the same page, which is good.

So "this avoid multi-threading issues" without mentioning "perf and"
would be more appropriate?

Thanks.