Date: Wed, 16 Aug 2017 09:08:08 +0530 From: Gautam <list@execve.net> To: Warner Losh <imp@bsdimp.com> Cc: freebsd-hackers <freebsd-hackers@freebsd.org> Subject: Re: Freebsd 11.0 - system freeze on intensive I/O Message-ID: <CAD9pFYCoodsEkMJ7NyDSBtCPJdUQMHokL0P8NofONYZnHE9%2Brw@mail.gmail.com> In-Reply-To: <CANCZdfr2h=PgVRxhX7-DXZhjkvEEMgV7pwhV5xSj%2B5Efe8ua%2BA@mail.gmail.com> References: <CAD9pFYAAy8jKcABNTun-Y3knrbUreQ7q1-CCj=323HgLMC5e6g@mail.gmail.com> <598ADB65.8060701@grosbein.net> <CALH631mEEcUwceh1UYhpF664SoEA4P%2BU87VEhrY-vnZrrQ%2Bw8g@mail.gmail.com> <B0B159BA-3C4A-4A5C-B3EB-CBF2CF251274@dsl-only.net> <CAD9pFYCxBO18GmRE6=-i==j3puJqgQ7bvPk7dmP%2B=T2hgbaAcw@mail.gmail.com> <CAD9pFYAyLpffrFUPOJya%2BG5cvkMNduY-j4M8PED9vS21RaDVOA@mail.gmail.com> <CANCZdfr2h=PgVRxhX7-DXZhjkvEEMgV7pwhV5xSj%2B5Efe8ua%2BA@mail.gmail.com>
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Hi, On Sat, Aug 12, 2017 at 8:53 PM, Warner Losh <imp@bsdimp.com> wrote: > > > On Fri, Aug 11, 2017 at 11:17 PM, Gautam <list@execve.net> wrote: > >> > =E2=80=8BOne update on this one. I installed a custom stable/11 kernel= and world >> (sched =3D 4BSD was the only change), and the problem >> is no longer seen. From my untrained eyes, it looks like some kind of sw= ap >> request starvation causing a hang when ULE is in use.=E2=80=8B >> > > I did some patches a few years ago that separated out geom requests into > their own uma map, if you wanted and hacked the swap pager to use that to > ensure that it always had BIOs available to do it's I/O. Maybe I should > dust them off and see if they help you. They didn't seem to help me too > much, but didn't hurt too much either. > > There's still the issue of some drivers not pre-allocating requests, whic= h > is what makes the deadlock possible in the first place. > > Warner > > I would be willing to try the patches and report back - although my understanding of FreeBSD inter=E2=80=8Bnals is next to zero; but can surely= try. =E2=80=8BThanks, Gautam =E2=80=8B
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