Date: Sun, 28 Nov 2010 02:24:21 -0600 From: Adam Vande More <amvandemore@gmail.com> To: Peter Jeremy <peterjeremy@acm.org> Cc: freebsd-stable@freebsd.org Subject: Re: idprio processes slowing down system Message-ID: <AANLkTiksuYmhG8UmDmCB3Hnq5xtNvuauD0Qni89C_rb-@mail.gmail.com> In-Reply-To: <20101128072624.GA76358@server.vk2pj.dyndns.org> References: <20101128072624.GA76358@server.vk2pj.dyndns.org>
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On Sun, Nov 28, 2010 at 1:26 AM, Peter Jeremy <peterjeremy@acm.org> wrote: > Since all the boinc processes are running at i31, why are they impacting > a buildkernel that runs with 0 nicety? > Someone please enlighten me if I'm wrong, but I'll take a stab at it. With the setup you presented you're going to have a lot of context switches as the buildworld is going to give plenty of oppurtunities for boinc processes to get some time. When it does switch out, the CPU cache is invalidated, then invalidated again when the buildworld preempts back. This is what makes it slow. If gcc was building one massive binary at that priority, you wouldn't have boinc getting much/any time. Since the buildworld is much more modular and consists of a large amount of small operations some CPU intentisive, some IO intensive, boinc can interrupt and impact overall performance even if the inital process was started at a much higher priority. I'm not sure how well ULE handles CPU affinity. Some other stuff I ran into earlier suggested there's room for improvement, but in your particular use case I'm not sure even ideal CPU affinity would improve things much. -- Adam Vande More
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