I believe the Windows default is to use the LFH on Vista and newer versions of Windows. The suggestion by Marcus Grimm to use _set_sbh_threshold() to enable use of the SBH (small block heap) may help under some usage scenarios on those platforms.
-Shane On Fri, Dec 17, 2010 at 6:29 PM, Doug <pa...@poweradmin.com> wrote: > I wonder if HeapSetInformation (which can enable a low-fragmentation heap) > would be helpful too. You can set it on the process > and the CRT heaps. Note that it's not available in Win2K and earlier. > > Doug > > -----Original Message----- > From: sqlite-users-boun...@sqlite.org > [mailto:sqlite-users-boun...@sqlite.org] On Behalf Of Marcus Grimm > Sent: Friday, December 17, 2010 9:21 AM > To: General Discussion of SQLite Database > Subject: Re: [sqlite] Windows performance problems associated with malloc() > >> An SQLite user has brought to our attention a performance issue in >> SQLite that seems to be associated with malloc(). If you have >> insights or corroborating experience with this issue please let me know. > > We recently had a malloc/free slowdown issue after changing to VS2008 in > combination with XP. > Not sure if it applies in your case but for us this helps: > -- > if( _get_sbh_threshold() < 512 ) > { > _set_sbh_threshold(512); > } > --- > > I'm unable to run your sqlite3.exe: MSVCR100.dll no found. > > Anyway, maybe the above helps. > > KInd regards > > Marcus > >> >> SQLite supports a "zero-malloc option" (see >> http://www.sqlite.org/malloc.html#memsys5 for details) which uses its >> own internal memory allocator rather than system malloc(). Earlier >> today, we patched the command-line shell to allow the zero-malloc >> option to be turned on. If you do: >> >> sqlite3 DATABASE >> >> then the regular system memory allocator is used, but if you say: >> >> sqlite3 -heap 100M DATABASE >> >> then the MEMSYS5 memory allocator will be used with a pool of 100MB of >> memory to work with. (You can adjust the size of your memory pool for >> whatever you need.) >> >> There are win32 and win64 builds of this updated command-line shell >> compiled using vs2010 here: >> >> http://www.sqlite.org/draft/download.html >> >> For certain full-text search queries against a large database, we are >> seeing speeds which are 3x faster when using "-heap 300M" (the memsys5 >> memory >> allocator) versus omitting the -heap option and thus using system >> malloc(). >> This is on windows7. Similar results are seen with both gcc and >> vs2010 builds. >> >> If you have any large queries that you can run on windows using the >> command-line shell, I would appreciate you timing those queries using >> the new shells from the download page, both with "-heap 300M" and >> without it, and letting me know about any performance differences you see. >> >> I also observe that compiling for 64-bit using vs2010 (not an option >> with my ancient version 2.95.3 gcc cross-compiler) that the queries >> are an additional 2x faster. I was surprised at the dramatic >> performance increase in going from 32-bit to 64-bit. Is such a >> speed-up typical? >> >> The use of "-heap 300M" seems to not make any performance difference >> on Linux. >> >> Any insights into why this is, what we are doing wrong, or what we can >> do to improve the performance of malloc() on windows will be >> appreciated. >> >> -- >> D. Richard Hipp >> d...@sqlite.org >> _______________________________________________ >> sqlite-users mailing list >> sqlite-users@sqlite.org >> http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users >> > > > _______________________________________________ > sqlite-users mailing list > sqlite-users@sqlite.org > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users > > > _______________________________________________ > sqlite-users mailing list > sqlite-users@sqlite.org > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users > _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
