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Subject: svn commit: r1709799 -
 /subversion/trunk/subversion/libsvn_fs_fs/fs_fs.c
Date: Wed, 21 Oct 2015 11:35:58 -0000
To: commits@subversion.apache.org
From: stefan2@apache.org
Message-Id: <20151021113559.3B5B33A0337@svn01-us-west.apache.org>

Author: stefan2
Date: Wed Oct 21 11:35:58 2015
New Revision: 1709799

URL: http://svn.apache.org/viewvc?rev=1709799&view=rev
Log:
Increase the default revprop pack size in FSFS from 4k to 16k.

Given that the manifest file is typically 8k to 10k already, the increase
in data transfer and processing overhead for random, uncached access is
a moderate 50%.  The revprop prefetching / temporary buffering needs fewer
manifest reads and fopen calls now such that the total CPU will actually
go down in typical scenarios.

On the physical side of things, we see a significant reduction in file
count, which reduces random I/O and the cost of copying repositories.

* subversion/libsvn_fs_fs/fs_fs.c
  (read_config): Increase the pack file size defaults by a factor of 4.
  (write_config): Update the docstring on the fsfs.conf template.

Modified:
    subversion/trunk/subversion/libsvn_fs_fs/fs_fs.c

Modified: subversion/trunk/subversion/libsvn_fs_fs/fs_fs.c
URL: http://svn.apache.org/viewvc/subversion/trunk/subversion/libsvn_fs_fs/fs_fs.c?rev=1709799&r1=1709798&r2=1709799&view=diff
==============================================================================
--- subversion/trunk/subversion/libsvn_fs_fs/fs_fs.c (original)
+++ subversion/trunk/subversion/libsvn_fs_fs/fs_fs.c Wed Oct 21 11:35:58 2015
@@ -754,8 +754,8 @@ read_config(fs_fs_data_t *ffd,
                                    CONFIG_SECTION_PACKED_REVPROPS,
                                    CONFIG_OPTION_REVPROP_PACK_SIZE,
                                    ffd->compress_packed_revprops
-                                       ? 0x10
-                                       : 0x4));
+                                       ? 0x40
+                                       : 0x10));
 
       ffd->revprop_pack_size *= 1024;
     }
@@ -962,9 +962,9 @@ write_config(svn_fs_t *fs,
 "### latency and CPU usage reading and changing individual revprops."        NL
 "### Values smaller than 4 kByte will not improve latency any further and "  NL
 "### quickly render revprop packing ineffective."                            NL
-"### revprop-pack-size is 4 kBytes by default for non-compressed revprop"    NL
-"### pack files and 16 kBytes when compression has been enabled."            NL
-"# " CONFIG_OPTION_REVPROP_PACK_SIZE " = 4"                                  NL
+"### revprop-pack-size is 16 kBytes by default for non-compressed revprop"   NL
+"### pack files and 64 kBytes when compression has been enabled."            NL
+"# " CONFIG_OPTION_REVPROP_PACK_SIZE " = 16"                                 NL
 "###"                                                                        NL
 "### To save disk space, packed revprop files may be compressed.  Standard"  NL
 "### revprops tend to allow for very effective compression.  Reading and"    NL