Ah, that's much better, thanks! --dave
johan...@sun.com wrote: > On Thu, Jun 25, 2009 at 04:55:14PM -0400, David Collier-Brown wrote: >> johan...@sun.com replied >>> I disagree with the premise that the free memory calculation isn't >>> useful because it doesn't count ZFS caches as free space. >> [big snip] >>> The space that's consumed by ZFS is in use and can't simply be peeled >>> off a free-list and used immediately. Adding a variable that counts >>> space used by ZFS as free is actually going to be more confusing. >> I worry that we're making a silent change to "all memory is >> considered used" again. If we are, we will have to kludge >> up a metric, like scan rate that spiked when we run out of memory. > > That's not what I said. > > There isn't a deterministic way to ascertain how much of the memory that > ZFS is consuming may be free'd when we perform an ARC reap operation. > Therefore, trying to create a beancounter that represents free memory in > use by ZFS isn't productive since there's no way to guarantee that the > number that's reported free could actually be free'd. If you don't want > ZFS to consume all of your memory, and want to keep memory out of the > ARC so it can always be allocated, there are a well documented set of > procedures for configuring limits on the size of the ARC. > > > -j > -- David Collier-Brown | Always do right. This will gratify Sun Microsystems, Toronto | some people and astonish the rest dav...@sun.com | -- Mark Twain cell: (647) 833-9377, home (416) 223-8968, bridge (877) 385-4099 code 506 9191# _______________________________________________ perf-discuss mailing list perf-discuss@opensolaris.org
