On Tue, Aug 17, 2010 at 3:29 PM, Dimitry Andric <dimi...@andric.com> wrote:
> On 2010-08-17 18:29, Alan Cox wrote: > > Try it again on a memory resident file with the MAP_PREFAULT_READ option > > that is provided by this patch: > > > > http://www.cs.rice.edu/~alc/MAP_PREFAULT_READ.patch<http://www.cs.rice.edu/%7Ealc/MAP_PREFAULT_READ.patch> > > A time trial gives: > > grep with normal mmap() 1396s > grep with prefault mmap() 1354s > grep with regular read() 1354s > > So normal mmap is ~3% slower, and prefault mmap does not seem to make > any measurable difference. I guess the added complexity is not really > worth it, for now. > Do you know what fraction of this time is being spent in the kernel? Does the value of "sysctl vm.pmap.pde.mappings" increase as a result of your test? If not, there is still room for improvement in the results with mmap(). Alan _______________________________________________ freebsd-current@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to "freebsd-current-unsubscr...@freebsd.org"
