Date: Fri, 14 Feb 2014 09:55:03 -0800 From: Adrian Chadd <adrian@freebsd.org> To: John Baldwin <jhb@freebsd.org> Cc: "freebsd-hackers@freebsd.org" <freebsd-hackers@freebsd.org>, Ryan Stone <rysto32@gmail.com>, "freebsd-arch@freebsd.org" <freebsd-arch@freebsd.org> Subject: Re: can the scheduler decide to schedule an interrupted but runnable thread on another CPU core? What are the implications for code? Message-ID: <CAJ-Vmo=vQ%2BMX%2Br3z6_Y4aJiWUBxXgXE7APjTsUysVPN2aoghXQ@mail.gmail.com> In-Reply-To: <201402141139.49158.jhb@freebsd.org> References: <CAJ-Vmo=7Nz1jqXy%2BrTQ7u9_ZP7jeFOKUJxU1O51tYJjvTUmWTg@mail.gmail.com> <CAJ-Vmommd7w_7RtkqgFGt%2BCVccqcsd8QLNOSXdXSRmmBPKEyYg@mail.gmail.com> <CAJ-VmondWeDjSepQOmNtC1h7wZG=ZQax0tHPMv%2BSSc7O2KZ3dQ@mail.gmail.com> <201402141139.49158.jhb@freebsd.org>
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On 14 February 2014 08:39, John Baldwin <jhb@freebsd.org> wrote: > On Friday, February 14, 2014 4:22:34 am Adrian Chadd wrote: >> Ok, so now I remember the other odd thing. >> >> I was seeing the sending context(s) jumping from one CPU to another >> during flowtable_insert_common(), around the locking bits. >> >> But I thread pinned all the sender user threads! >> >> So, why would the senders still be scheduled on other CPUs if I've >> pinned the userland threads? >> >> (and yes, I verified that the userland threads weren't moving around.) > > Can you clarify a bit? It's not clear how sender thraeds differ from > userland threads differ from sender user threads. (I.e. one reading > is that these are all the same thing and should thus all be pinned > (I assume you mean using cpuset to bind them to specific cores rather > than sched_pin)) Yup, I'm doing a manual, poor-mans RSS in lieu of merging in roberts stuff: * the userland threads are using the cpuset call to map a thread into a cpuset, yes * the NIC TX/RX ring routines in cxgbe are pinned to the same CPU as the userland threads -a
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