On Fri, Aug 3, 2012 at 4:30 PM, Josh Berkus <josh@xxxxxxxxxxxx> wrote: > On 7/30/12 10:09 AM, Scott Marlowe wrote: >> I think the zone_reclaim gets turned on with a high ratio. If the >> inter node costs were the same, and the intranode costs dropped in >> half, zone reclaim would likely get turned on at boot time. > > We've been seeing a major problem with zone_reclaim and Linux, in that > Linux won't use the FS cache on the "distant" RAM *at all* if it thinks > that RAM is distant enough. Thus, you get instances of seeing only half > of RAM used for FS cache, even though the database is 5X larger than RAM. > > This is poor design on Linux's part, since even the distant RAM is > faster than disk. For now, we've been disabling zone_reclaim entirely. I haven't run into this, but we were running ubuntu 10.04 LTS. What kernel were you running when this happened? I'd love to see a test case on this, as it seems like a major regression if it's on newer kernels, and we're looking at running 12.04 LTS soon on one of our bigger machines. -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
