Date: Sat, 10 May 2014 19:47:01 +0000 (UTC) From: Alan Cox <alc@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r265850 - head/sys/vm Message-ID: <201405101947.s4AJl13j004572@svn.freebsd.org>
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Author: alc Date: Sat May 10 19:47:00 2014 New Revision: 265850 URL: http://svnweb.freebsd.org/changeset/base/265850 Log: About 9% of the pmap_protect() calls being performed by vm_map_copy_entry() are unnecessary. Eliminate the unnecessary calls. Reviewed by: kib MFC after: 1 week Sponsored by: EMC / Isilon Storage Division Modified: head/sys/vm/vm_map.c Modified: head/sys/vm/vm_map.c ============================================================================== --- head/sys/vm/vm_map.c Sat May 10 19:18:49 2014 (r265849) +++ head/sys/vm/vm_map.c Sat May 10 19:47:00 2014 (r265850) @@ -3023,7 +3023,8 @@ vm_map_copy_entry( * If the source entry is marked needs_copy, it is already * write-protected. */ - if ((src_entry->eflags & MAP_ENTRY_NEEDS_COPY) == 0) { + if ((src_entry->eflags & MAP_ENTRY_NEEDS_COPY) == 0 && + (src_entry->protection & VM_PROT_WRITE) != 0) { pmap_protect(src_map->pmap, src_entry->start, src_entry->end,
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