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Re: svn commit: r1586922 - in /subversion/trunk/subversion: include/private/svn_io_private.h include/svn_types.h libsvn_subr/io.c libsvn_subr/stream.c

From: Ivan Zhakov <ivan_at_visualsvn.com>
Date: Fri, 18 Apr 2014 12:06:40 +0400

On 14 April 2014 20:11, Ivan Zhakov <ivan_at_visualsvn.com> wrote:
> On 13 April 2014 08:40, <stefan2_at_apache.org> wrote:
>> Author: stefan2
>> Date: Sun Apr 13 04:40:40 2014
>> New Revision: 1586922
>> URL: http://svn.apache.org/r1586922
>> Log:
>> Speed up file / stream comparison, i.e. minimize the processing overhead
>> for finding the first mismatch.
>> The approach is two-sided. Instead of fetching SVN__STREAM_CHUNK_SIZE
>> from all sources before comparing data, we start with a much lower 4kB
>> and increase the chunk size until we reach SVN__STREAM_CHUNK_SIZE while
>> making sure that all reads are naturally aligned. So, we quickly find
>> mismatches near the beginning of the file.
>> On the other end side, we bump the SVN__STREAM_CHUNK_SIZE to 64kB which
>> gives better throughput for longer distances to the first mismatch -
>> without causing ill effects in APR's memory management.
>> * subversion/include/svn_types.h
>> (SVN__STREAM_CHUNK_SIZE): Bump to 64k and add some documentation on
>> the general restrictions for future changes.
> Hi Stefan,
> You effectively reverted my recent fix (r1581296) for high memory
> usage with many repositories open at the same time (about 500k per
> repository. Also please consider r857671 and discussion before that
> commit:
> http://svn.haxx.se/dev/archive-2004-11/0123.shtml
> So please revert.
Sorry, may be I was not clear enough, but I was vetoing this change.
Given no reply, I'm going to revert it.

Ivan Zhakov
CTO | VisualSVN | http://www.visualsvn.com
Received on 2014-04-18 10:07:37 CEST

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