Hi,
Attached is an experimental patch to estimate the size of the
DynamicMMap from the size of the Release files that the cache is
generated from, instead of using a hardcoded estimate of 24MB.
I discarded my test builds (and accidentally the notes) about it
when I expected DynamicMMap to be removed entirely. IIRC, the
estimate is about double the size of the final cache; it should be
the size of the uncompressed Packages files (23MB for Lenny, 25MB
for Sid).
Patch is for apt-0.7.18
Steve
Sat Nov 29 12:23:08 GMT 2008 Steve Cotton <st...@s.cotton.clara.co.uk>
* 380509: set the size of the DynamicMMap based on the size of the package files
This changes pkgMakeStatusCache, but not pkgMakeOnlyStatusCache.
The latter is appears to only be called from debDpkgDB::ReadyPkgCache, which
itself is exported, but only called in two test files scratch.cc and
testextract.cc (searched Apt and Aptitude for others).
diff -rN -u old-apt-0.7.18.steve.2/apt-pkg/pkgcachegen.cc new-apt-0.7.18.steve.2/apt-pkg/pkgcachegen.cc
--- old-apt-0.7.18.steve.2/apt-pkg/pkgcachegen.cc 2008-11-29 12:40:25.000000000 +0000
+++ new-apt-0.7.18.steve.2/apt-pkg/pkgcachegen.cc 2008-11-29 12:40:25.000000000 +0000
@@ -793,8 +793,6 @@
bool pkgMakeStatusCache(pkgSourceList &List,OpProgress &Progress,
MMap **OutMap,bool AllowMem)
{
- unsigned long MapSize = _config->FindI("APT::Cache-Limit",24*1024*1024);
-
vector<pkgIndexFile *> Files;
for (vector<metaIndex *>::const_iterator i = List.begin();
i != List.end();
@@ -836,7 +834,10 @@
}
/* At this point we know we need to reconstruct the package cache,
- begin. */
+ begin by allocating an mmap'd file as large as the total of the
+ input files; all unused space will be truncated afterwards. */
+ unsigned long DefaultMapSize = ComputeSize(Files.begin(),Files.end());
+ unsigned long MapSize = _config->FindI("APT::Cache-Limit", DefaultMapSize);
SPtr<FileFd> CacheF;
SPtr<DynamicMMap> Map;
if (Writeable == true && CacheFile.empty() == false)
