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f9efa9c784
This calls unlock_up sooner in btrfs_search_slot in order to decrease the amount of work done with the higher level tree locks held. Also, it changes btrfs_tree_lock to spin for a big against the page lock before scheduling. This makes a big difference in context switch rate under highly contended workloads. Longer term, a better locking structure is needed than the page lock. Signed-off-by: Chris Mason <chris.mason@oracle.com>
60 lines
1.5 KiB
C
60 lines
1.5 KiB
C
/*
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* Copyright (C) 2008 Oracle. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public
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* License v2 as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public
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* License along with this program; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 021110-1307, USA.
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*/
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#include <linux/sched.h>
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#include <linux/gfp.h>
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#include <linux/pagemap.h>
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#include <linux/spinlock.h>
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#include <linux/page-flags.h>
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#include <linux/bug.h>
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#include "ctree.h"
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#include "extent_io.h"
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#include "locking.h"
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int btrfs_tree_lock(struct extent_buffer *eb)
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{
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int i;
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if (!TestSetPageLocked(eb->first_page))
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return 0;
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for (i = 0; i < 512; i++) {
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cpu_relax();
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if (!TestSetPageLocked(eb->first_page))
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return 0;
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}
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cpu_relax();
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lock_page(eb->first_page);
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return 0;
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}
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int btrfs_try_tree_lock(struct extent_buffer *eb)
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{
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return TestSetPageLocked(eb->first_page);
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}
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int btrfs_tree_unlock(struct extent_buffer *eb)
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{
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WARN_ON(!PageLocked(eb->first_page));
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unlock_page(eb->first_page);
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return 0;
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}
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int btrfs_tree_locked(struct extent_buffer *eb)
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{
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return PageLocked(eb->first_page);
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}
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