[PATCH V2] posix: insert seek between reads and writes on Solaris (issue4943)

[Augie Fackler]

On Mon, Dec 07, 2015 at 02:06:56PM -0800, Pierre-Yves David wrote:
> On 12/07/2015 02:01 PM, Matt Mackall wrote:
> >On Mon, 2015-12-07 at 13:27 -0800, Pierre-Yves David wrote:
> >>
> >>On 12/07/2015 12:24 PM, Matt Mackall wrote:
> >>>On Sat, 2015-12-05 at 21:26 -0800, Gregory Szorc wrote:
> >>>>On Fri, Dec 4, 2015 at 6:51 PM, Pierre-Yves David <
> >>>>pierre-yves.david at ens-lyon.org> wrote:
> >>>So I'm frankly leaning towards just inserting a seek in the revlog
> >>>code
> >>>to be safe.
> >>
> >>You mean doing the seek in all cases/OSes, right. This seems
> >>reasonable
> >>(modulo proper documentation)
> >>
> >>What would be the downside of it? Is there an expected performance
> >>hit?
> >
> >Unknown, but probably minimal. The seek still probably goes through the
> >stdio buffer code.. and just injects some sanity. Correctly-written
> >buffer code can potentially still elide sending the seek onto the
> >kernel. And even if it doesn't.. a simple syscall like this on Linux is
> >actually pretty similar in speed to a Python function call.
>
> So any object to just doing it?

I'm in favor of just inserting the seek in the revlog code and doing
an out-of-schedule release to fix solaris folks.

>
> --
> Pierre-Yves David
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