Date: Sun, 2 Feb 2020 03:20:53 +0800 From: Li-Wen Hsu <lwhsu@freebsd.org> To: Jeff Roberson <jeff@freebsd.org> Cc: src-committers <src-committers@freebsd.org>, svn-src-all <svn-src-all@freebsd.org>, svn-src-head <svn-src-head@freebsd.org> Subject: Re: svn commit: r357314 - in head/sys: conf kern sys vm Message-ID: <CAKBkRUyWV6RuCpRHDda%2B5D1xhewwRnHCFPGehiAgBo9GK5MEWA@mail.gmail.com> In-Reply-To: <202001310049.00V0np1a077223@repo.freebsd.org> References: <202001310049.00V0np1a077223@repo.freebsd.org>
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On Fri, Jan 31, 2020 at 8:50 AM Jeff Roberson <jeff@freebsd.org> wrote: > > Author: jeff > Date: Fri Jan 31 00:49:51 2020 > New Revision: 357314 > URL: https://svnweb.freebsd.org/changeset/base/357314 > > Log: > Implement a safe memory reclamation feature that is tightly coupled with UMA. > > This is in the same family of algorithms as Epoch/QSBR/RCU/PARSEC but is > a unique algorithm. This has 3x the performance of epoch in a write heavy > workload with less than half of the read side cost. The memory overhead > is significantly lessened by limiting the free-to-use latency. A synthetic > test uses 1/20th of the memory vs Epoch. There is significant further > discussion in the comments and code review. > > This code should be considered experimental. I will write a man page after > it has settled. After further validation the VM will begin using this > feature to permit lockless page lookups. > > Both markj and cperciva tested on arm64 at large core counts to verify > fences on weaker ordering architectures. I will commit a stress testing > tool in a follow-up. > > Reviewed by: mmacy, markj, rlibby, hselasky > Discussed with: sbahara > Differential Revision: https://reviews.freebsd.org/D22586 I found it might cause i386 boot fail: Kernel page fault with the following non-sleepable locks held: exclusive sleep mutex kernel arena (kernel arena) r = 0 (0x1d99d80) locked @ /usr/src/sys/kern/subr_vmem.c:1344 Full backtrace is available at https://ci.freebsd.org/job/FreeBSD-head-i386-test/8275/console Please help checking this. Thanks, Li-Wen
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