Date: Mon, 8 Jul 2019 19:02:40 +0000 (UTC) From: Mark Johnston <markj@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r349841 - head/sys/vm Message-ID: <201907081902.x68J2eOx063494@repo.freebsd.org>
next in thread | raw e-mail | index | archive | help
Author: markj Date: Mon Jul 8 19:02:40 2019 New Revision: 349841 URL: https://svnweb.freebsd.org/changeset/base/349841 Log: Elide the vm_reserv_free_page() call when PG_PCPU_CACHE is set. Pages with PG_PCPU_CACHE set cannot have been allocated from a reservation, so as an optimization, skip the call to vm_reserv_free_page() in this case. Otherwise, the access of the corresponding reservation structure often results in a cache miss. Reviewed by: alc, kib Discussed with: jeff MFC after: 2 weeks Sponsored by: Netflix Differential Revision: https://reviews.freebsd.org/D20859 Modified: head/sys/vm/vm_page.c Modified: head/sys/vm/vm_page.c ============================================================================== --- head/sys/vm/vm_page.c Mon Jul 8 18:56:30 2019 (r349840) +++ head/sys/vm/vm_page.c Mon Jul 8 19:02:40 2019 (r349841) @@ -3491,7 +3491,12 @@ vm_page_free_prep(vm_page_t m) pmap_page_set_memattr(m, VM_MEMATTR_DEFAULT); #if VM_NRESERVLEVEL > 0 - if (vm_reserv_free_page(m)) + /* + * Determine whether the page belongs to a reservation. If the page was + * allocated from a per-CPU cache, it cannot belong to a reservation, so + * as an optimization, we avoid the check in that case. + */ + if ((m->flags & PG_PCPU_CACHE) == 0 && vm_reserv_free_page(m)) return (false); #endif
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?201907081902.x68J2eOx063494>