Author: markj Date: Wed Sep 2 19:59:25 2020 New Revision: 365275 URL: https://svnweb.freebsd.org/changeset/base/365275
Log: Avoid unnecessary object locking in vm_page_grab_pages_unlocked(). We were needlessly acquiring the object lock to call vm_page_grab_pages() even when all of the requested pages were looked up locklessly. Fix that, stop testing for count == 0 in vm_page_grab_pages(), and add assertions to help catch this kind of mistake. Reported by: cem Reviewed by: alc, cem, dougm, jeff Differential Revision: https://reviews.freebsd.org/D26304 Modified: head/sys/vm/vm_page.c Modified: head/sys/vm/vm_page.c ============================================================================== --- head/sys/vm/vm_page.c Wed Sep 2 19:37:47 2020 (r365274) +++ head/sys/vm/vm_page.c Wed Sep 2 19:59:25 2020 (r365275) @@ -4724,12 +4724,11 @@ vm_page_grab_pages(vm_object_t object, vm_pindex_t pin VM_OBJECT_ASSERT_WLOCKED(object); KASSERT(((u_int)allocflags >> VM_ALLOC_COUNT_SHIFT) == 0, ("vm_page_grap_pages: VM_ALLOC_COUNT() is not allowed")); + KASSERT(count > 0, + ("vm_page_grab_pages: invalid page count %d", count)); vm_page_grab_check(allocflags); pflags = vm_page_grab_pflags(allocflags); - if (count == 0) - return (0); - i = 0; retrylookup: m = vm_radix_lookup_le(&object->rtree, pindex + i); @@ -4783,6 +4782,8 @@ vm_page_grab_pages_unlocked(vm_object_t object, vm_pin int flags; int i; + KASSERT(count > 0, + ("vm_page_grab_pages_unlocked: invalid page count %d", count)); vm_page_grab_check(allocflags); /* @@ -4805,7 +4806,7 @@ vm_page_grab_pages_unlocked(vm_object_t object, vm_pin vm_page_grab_release(m, allocflags); pred = ma[i] = m; } - if ((allocflags & VM_ALLOC_NOCREAT) != 0) + if (i == count || (allocflags & VM_ALLOC_NOCREAT) != 0) return (i); count -= i; VM_OBJECT_WLOCK(object); _______________________________________________ svn-src-head@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
