Author: alc Date: Fri May 27 06:05:12 2016 New Revision: 300826 URL: https://svnweb.freebsd.org/changeset/base/300826
Log: Use vm_page_replace_checked() instead of vm_page_rename() for implementing optimized copy-on-write faults. This has two advantages: (1) one less radix tree operation is performed and (2) vm_page_replace_checked() cannot fail, making the code simpler. Submitted by: Ryan Libby Reviewed by: kib Sponsored by: EMC / Isilon Storage Division Differential Revision: https://reviews.freebsd.org/D4478 Modified: head/sys/vm/vm_fault.c Modified: head/sys/vm/vm_fault.c ============================================================================== --- head/sys/vm/vm_fault.c Fri May 27 05:58:53 2016 (r300825) +++ head/sys/vm/vm_fault.c Fri May 27 06:05:12 2016 (r300826) @@ -799,26 +799,15 @@ vnode_locked: * We don't chase down the shadow chain */ fs.object == fs.first_object->backing_object) { - /* - * get rid of the unnecessary page - */ - vm_page_lock(fs.first_m); - vm_page_remove(fs.first_m); - vm_page_unlock(fs.first_m); - /* - * grab the page and put it into the - * process'es object. The page is - * automatically made dirty. - */ - if (vm_page_rename(fs.m, fs.first_object, - fs.first_pindex)) { - VM_OBJECT_WUNLOCK(fs.first_object); - unlock_and_deallocate(&fs); - goto RetryFault; - } + vm_page_lock(fs.m); + vm_page_remove(fs.m); + vm_page_unlock(fs.m); vm_page_lock(fs.first_m); + vm_page_replace_checked(fs.m, fs.first_object, + fs.first_pindex, fs.first_m); vm_page_free(fs.first_m); vm_page_unlock(fs.first_m); + vm_page_dirty(fs.m); #if VM_NRESERVLEVEL > 0 /* * Rename the reservation. @@ -827,6 +816,10 @@ vnode_locked: fs.object, OFF_TO_IDX( fs.first_object->backing_object_offset)); #endif + /* + * Removing the page from the backing object + * unbusied it. + */ vm_page_xbusy(fs.m); fs.first_m = fs.m; fs.m = NULL; _______________________________________________ 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"
