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Re: svn commit: r17572 - in trunk/subversion: libsvn_ra_dav libsvn_repos libsvn_subr

From: Erik Huelsmann <ehuels_at_gmail.com>
Date: 2005-12-01 11:28:39 CET

On 12/1/05, Peter N. Lundblad <peter@famlundblad.se> wrote:
> On Thu, 1 Dec 2005, Erik Huelsmann wrote:
> > On 12/1/05, Greg Hudson <ghudson@mit.edu> wrote:
> > On Wed, 2005-11-30 at 17:48 -0600, dionisos@tigris.org wrote:
> > > Create a subpool to allocate SVN_STREAM_CHUNK_SIZE buffers. Just before
> > > completing successfully, clean the subpool to free the 100kB buffer.
> >
> > I don't understand the need for this. If the function is being called
> > in a loop, the loop should be using an iteration pool. If the function
> > is not being called from a loop, 100K is noise.
> >This commit is a consequence of lundblad 'complaining' about the fact
> >that I left a buffer allocated in libsvn_subr/subst.c. That buffer was
> >about the same size. So, I looked where else the buffer was allocated
> >and disposed of, moving the allocation to a subpool if it wasn't
> >already.
> I was complaining about a case where two such buffers were used by a
> stream object. That stretches the "noise" level a bit too far IMO. Say you
> use a few such streams (not in a loop). Then we start to waste megabytes
> just for too big buffers.
> As I've stated before, my preferred fix is to shrink the buffer size used
> from 100K to something more sensible (like 8K or 16K). There is no point
> in using such a large chunk and it has some problems. Then the above
> commit is unnecessary since allocating some kilobytes really *is* noise...

Correct. Peter expressed the same to me yesterday on irc. He also
referred to a discussion he had with Tobias Ringstrom about this,
trying to choose a "good" buffer size. He has pinged Tobias about the
issue again.

Last time, no real action was taken and since I had the change in my
working copy anyway, we have an intermediate solution now. As soon as
someone finds an efficient yet not-very-big buffer size to use, we can
back out this change and use a different buffer size.


Received on Thu Dec 1 11:30:38 2005

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