Date: Fri, 18 Mar 2016 12:01:37 -0700 From: Stanislav Sedov <stas@FreeBSD.org> To: John Baldwin <jhb@freebsd.org> Cc: Adrian Chadd <adrian.chadd@gmail.com>, Konstantin Belousov <kostikbel@gmail.com>, "freebsd-hackers@freebsd.org" <freebsd-hackers@freebsd.org> Subject: Re: Peformance issues with r278325 Message-ID: <A6D0C094-9402-49D6-832D-4BA9C2A7384F@FreeBSD.org> In-Reply-To: <8EE51E0E-41F4-4B5A-A755-B58E8E1D1776@FreeBSD.org> References: <FA50A68E-7F3D-4361-8A8A-EB7F97EF3D00@FreeBSD.org> <8403291.NqUNo0Qq5W@ralph.baldwin.cx> <CAJ-VmonUdHRJ0jcFphqXi1w2PwbDycLG190Yd5z8JQWGxW_1iQ@mail.gmail.com> <3277812.DVsZx4uMun@ralph.baldwin.cx> <8EE51E0E-41F4-4B5A-A755-B58E8E1D1776@FreeBSD.org>
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> On Mar 18, 2016, at 11:16 AM, Stanislav Sedov <stas@freebsd.org> = wrote: >=20 > FWIW we are currently testing the delay '1' change. Unfortunately, = the test is > not easy to repeat (we didn't find a synthetic one yet that results in = the same > outcome), so it does take more time that I would like. Will follow up = with the=20 > results. >=20 > We did try HEAD as well a while ago, and although it exhibited the = same pattern. > However it did not utilize the x2apic unfortunately, as it does seem = to be disables > in the BIOS (FreeBSD reports it being disables in the DMAR table). >=20 > Thanks for looking into it! >=20 Replying to my own message. The `delay 1` test was a success, we were not able to reproduce the same = issues as we had with a 5us delay in that loop. So perhaps we should commit = the delay change into stable/10 instead of reverting the code altogether (I assume = the original change was done to solve a real issue?). -- Stanislav Sedov ST4096-RIPE
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