On Thu, Oct 04, 2007 at 06:59:56PM +0200, Roch - PAE wrote: > Nicolas Williams writes: > > On Thu, Oct 04, 2007 at 03:49:12PM +0200, Roch - PAE wrote: > > > So the DB memory pages should not be _contented_ for. > > > > What if your executable text, and pretty much everything lives on ZFS? > > You don't want to content for the memory caching those things either. > > It's not just the DB's memory you don't want to contend for. > > On the read side, > > We're talking here about 1000 disks each running 35 > concurrent I/Os of 8K, so a footprint of 250MB, to stage a > ton of work.
I'm not sure what you mean, but extra copies and memory just to stage the I/Os is not the same as the systemic memory pressure issue. Now, I'm _speculating_ as to what the real problem is, but it seems very likely that putting things in the cache that needn't be there would push out things that should be there, and since restoring those things to the cache later would cost I/Os... _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
