Date: Tue, 6 Nov 2012 18:51:37 -0700 From: "Samuel J. Greear" <sjg@evilcode.net> To: Yuri <yuri@rawbw.com> Cc: freebsd-hackers@freebsd.org Subject: Re: pgbench performance is lagging compared to Linux and DragonflyBSD? Message-ID: <CANY-Wm9iHS92_CzDJUCs1COC7-v0xt%2BT%2BCqrMq%2BPkshZ04UPtQ@mail.gmail.com> In-Reply-To: <50997AB8.40607@rawbw.com> References: <50980ADD.4010402@rawbw.com> <CAGH67wScvnE7gYzVVtfehYbVfM465vrLjP9bX4KXSp8Sq-25mA@mail.gmail.com> <50994FE0.2070205@rawbw.com> <CANY-Wm9nTPy5A3Eygb4BQmz60a8ose--3veoQHwFj3p66BFB8Q@mail.gmail.com> <50997AB8.40607@rawbw.com>
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On Tue, Nov 6, 2012 at 2:01 PM, Yuri <yuri@rawbw.com> wrote: > On 11/06/2012 11:10, Samuel J. Greear wrote: >> >> Single and multi-socket hardware are not really directly comparable in >> PostgreSQL tests. > > > So if the CPUs are split between sockets, would such system generally > perform better or worse with PostgeSQL vs. non-split situation? > > Yuri Unless the algorithms you are testing are able to operate entirely out of the processors caches (and PostgreSQL does not fall into that category) performance will be generally lower as you add sockets. FreeBSD's ULE scheduler is aware of this and takes it into account, but the performance ULE is able to maintain across sockets (this applies to other OS's schedulers too) is more damage control than anything else. Sam
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