Date: Thu, 17 May 2018 10:16:20 +0000 (UTC) From: Andriy Gapon <avg@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r333707 - head/sys/x86/x86 Message-ID: <201805171016.w4HAGKre037616@repo.freebsd.org>
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Author: avg Date: Thu May 17 10:16:20 2018 New Revision: 333707 URL: https://svnweb.freebsd.org/changeset/base/333707 Log: fix a problem with bad performance after wakeup caused by r333321 This change reverts a "while here" part of r333321 that moved clearing of suspended_cpus to an earlier place. Apparently, there can be a problem when modifying (shared) memory before restoring proper cache attributes. So, to be safe, move the clearing to the old place. Many thanks to Johannes Lundberg for bisecting the changes to that particular commit and then bisecting the commit to the particular change. Reported by: many Debugged by: Johannes Lundberg <johalun0@gmail.com> MFC after: 1 week X-MFC with: r333321 Modified: head/sys/x86/x86/mp_x86.c Modified: head/sys/x86/x86/mp_x86.c ============================================================================== --- head/sys/x86/x86/mp_x86.c Thu May 17 10:13:18 2018 (r333706) +++ head/sys/x86/x86/mp_x86.c Thu May 17 10:16:20 2018 (r333707) @@ -1457,8 +1457,6 @@ cpususpend_handler(void) */ wbinvd(); } else { - /* Indicate that we have restarted and restored the context. */ - CPU_CLR_ATOMIC(cpu, &suspended_cpus); #ifdef __amd64__ fpuresume(susppcbs[cpu]->sp_fpususpend); #else @@ -1468,6 +1466,9 @@ cpususpend_handler(void) initializecpu(); PCPU_SET(switchtime, 0); PCPU_SET(switchticks, ticks); + + /* Indicate that we have restarted and restored the context. */ + CPU_CLR_ATOMIC(cpu, &suspended_cpus); } /* Wait for resume directive */
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