On Thu, Apr 4, 2013 at 9:22 AM, Teg <t...@djii.com> wrote: > Hello Richard, > > How much do you map at a time?
The default on windows is currently 256MiB. You can adjust this number up or down using a pragma. Or you can change it at compile-time or start-time. > I've virtually abandoned memory mapped > files in Win32 because of address space limitations. There's a 2 GB > address space limit in Win32 (most of the time) so, if the > combination of allocated RAM and memory mapped file size bump into the > limit, the memory map will fail. Win64 doesn't have this limit. It'll > fail if it can't get a contiguous block of address space too. > > C > > Thursday, April 4, 2013, 8:02:34 AM, you wrote: > > RH> By making use of memory-mapped I/O, the current trunk of SQLite (which > will > RH> eventually become version 3.7.17 after much more refinement and > testing) > RH> can be as much as twice as fast, on some platforms and under some > RH> workloads. We would like to encourage people to try out the new code > and > RH> report both success and failure. Snapshots of the amalgamation can be > RH> found at > > RH> http://www.sqlite.org/draft/download.html > > RH> Links to the relevant documentation can bee seen at > > RH> http://www.sqlite.org/draft/releaselog/3_7_17.html > > RH> The memory-mapped I/O is only enabled for windows, linux, mac OS-X, and > RH> solaris. We have found that it does not work on OpenBSD, for reasons > we > RH> have not yet been able to uncove; but as a precaution, memory mapped > I/O is > RH> disabled by default on all of the *BSDs until we understand the > problem. > RH> The biggest performance gains occur on windows, mac, and solaris. The > new > RH> code is also faster on linux, but not by as big a factor. The speed > RH> improvement is also heavily dependent upon workload. Some operations > can > RH> be almost twice as faster. For others, there is no measurable speed > RH> improvement. > > RH> Your feedback on whether or not the new code is faster for you, and > whether > RH> or not it even works for you, is very important to us. Thanks for > giving > RH> the new code a try. > > > > > -- > Best regards, > Teg mailto:t...@djii.com > > _______________________________________________ > sqlite-users mailing list > sqlite-users@sqlite.org > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users > -- D. Richard Hipp d...@sqlite.org _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
