On Tue, Jun 9, 2009 at 11:15 PM, Dmitry Morozovsky<ma...@rinet.ru> wrote: > Kip, > > On Wed, 10 Jun 2009, Kip Macy wrote: > > KM> Author: kmacy > KM> Date: Wed Jun 10 01:21:32 2009 > KM> New Revision: 193878 > KM> URL: http://svn.freebsd.org/changeset/base/193878 > KM> > KM> Log: > KM> As far as I can tell systems that have less than 4GB are more often hurt > KM> by prefetched than helped. On i386 systems and systems with less than > 4GB, > KM> prefetch is now disabled by default. I've added a prefetch enable > tunable, to > KM> enable prefetching for those systems. The prefetch disable tunable will > continue > KM> to unconditionally disable prefetching. > KM> > > [snip] > > KM> +extern int zfs_prefetch_disable; > KM> +extern int zfs_prefetch_enable; > > [snip] > > Before the interface is not settled in stone, don't you think simple bool > zfs_prefetch tunable (defauled to what looks more reasonable to partucilar > arch/memsize) is more clean and straightforward? >
Yes. But the semantics I want don't lend themselves well to a boolean. I want it to default to off for i386 and amd64 w/ < 4GB and on for amd64 > 4GB. However, I want it to be possible for users with larger memory systems to disable it and users with smaller memory systems to enable it. The only way a simple boolean would work would be if it were zfs_prefetch_non_default_behavior, which I think is even more confusing than what I have now. Cheers, Kip _______________________________________________ svn-src-all@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
