Date: Wed, 19 Feb 2014 11:51:23 -0800 From: Adrian Chadd <adrian@freebsd.org> To: Alexander Motin <mav@freebsd.org> Cc: Jeffrey Faden <jeffreyatw@gmail.com>, freebsd-current <freebsd-current@freebsd.org>, "freebsd-arch@freebsd.org" <freebsd-arch@freebsd.org> Subject: Re: [rfc] bind per-cpu timeout threads to each CPU Message-ID: <CAJ-VmokQ_C=YVpk41_r-QakB46_RWRe0didq1_RrZBMS7hDX-A@mail.gmail.com> In-Reply-To: <530508B7.7060102@FreeBSD.org> References: <530508B7.7060102@FreeBSD.org>
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On 19 February 2014 11:40, Alexander Motin <mav@freebsd.org> wrote: > Hi. > > Clock interrupt threads, same as other ones are only softly bound to > specific CPUs by scheduler preferring to run them on CPUs where they are > scheduled. So far that was enough to balance load, but allowed threads to > migrate, if needed. Is it too flexible for some use case? I saw it migrate under enough CPU load / pressure, right smack bang in the middle of doing TCP processing. So if we're moving towards supporting (among others) a pcbgroup / RSS hash style work load distribution across CPUs to minimise per-connection lock contention, we really don't want the scheduler to decide it can schedule things on other CPUs under enough pressure. That'll just make things worse. -a
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