On Wed, Nov 05, 2003 at 01:25:43AM -0500, Vivek Pai wrote: > Mike Silbersack wrote: > >On Tue, 4 Nov 2003, Vivek Pai wrote: > >>The one other aspect of this is that sf_bufs mappings are maintained for > >>a configurable amount of time, reducing the number of TLB ops. You can > >>specify the parameter for how long, ranging from -1 (no coalescing at > >>all), 0 (coalesce, but free immediately after last holder release), to > >>any other time. Obviously, any value above 0 will increase the amount of > >>wired memory at any given point in time, but it's configurable. > > > >Ah, I missed that point. Did your testing show the caching part of the > >functionality to be significant? > > I think it buys us a small gain (a few percent) under static-content > workloads, and a little less under SpecWeb99, where more time is spent > in dynamic content. However, it's almost free - the additional > complexity beyond just coalescing is hooking into the timer to free > unused mappings.
I think it's reasonable to expect a more pronounced effect on i386 SMP. In order to maintain TLB coherence, we issue two interprocessor interrupts _per_page_ transmitted by sendfile(2). Alan _______________________________________________ [EMAIL PROTECTED] mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "[EMAIL PROTECTED]"
