From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760745AbYCCAR7 (ORCPT ); Sun, 2 Mar 2008 19:17:59 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757785AbYCCARF (ORCPT ); Sun, 2 Mar 2008 19:17:05 -0500 Received: from cantor2.suse.de ([195.135.220.15]:45651 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757332AbYCCARB (ORCPT ); Sun, 2 Mar 2008 19:17:01 -0500 From: NeilBrown To: Andrew Morton Date: Mon, 3 Mar 2008 11:17:11 +1100 Message-Id: <1080303001711.23593@suse.de> X-face: [Gw_3E*Gng}4rRrKRYotwlE?.2|**#s9D Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On an md array with a write-intent bitmap, a thread wakes up every few seconds and scans the bitmap looking for work to do. If the array is idle, there will be no work to do, but a lot of scanning is done to discover this. So cache the fact that the bitmap is completely clean, and avoid scanning the whole bitmap when the cache is known to be clean. Signed-off-by: Neil Brown ### Diffstat output ./drivers/md/bitmap.c | 19 +++++++++++++++++-- ./include/linux/raid/bitmap.h | 2 ++ 2 files changed, 19 insertions(+), 2 deletions(-) diff .prev/drivers/md/bitmap.c ./drivers/md/bitmap.c --- .prev/drivers/md/bitmap.c 2008-02-22 15:45:56.000000000 +1100 +++ ./drivers/md/bitmap.c 2008-02-22 15:45:56.000000000 +1100 @@ -1047,6 +1047,11 @@ void bitmap_daemon_work(struct bitmap *b if (time_before(jiffies, bitmap->daemon_lastrun + bitmap->daemon_sleep*HZ)) return; bitmap->daemon_lastrun = jiffies; + if (bitmap->allclean) { + bitmap->mddev->thread->timeout = MAX_SCHEDULE_TIMEOUT; + return; + } + bitmap->allclean = 1; for (j = 0; j < bitmap->chunks; j++) { bitmap_counter_t *bmc; @@ -1068,8 +1073,10 @@ void bitmap_daemon_work(struct bitmap *b clear_page_attr(bitmap, page, BITMAP_PAGE_NEEDWRITE); spin_unlock_irqrestore(&bitmap->lock, flags); - if (need_write) + if (need_write) { write_page(bitmap, page, 0); + bitmap->allclean = 0; + } continue; } @@ -1098,6 +1105,9 @@ void bitmap_daemon_work(struct bitmap *b /* if (j < 100) printk("bitmap: j=%lu, *bmc = 0x%x\n", j, *bmc); */ + if (*bmc) + bitmap->allclean = 0; + if (*bmc == 2) { *bmc=1; /* maybe clear the bit next time */ set_page_attr(bitmap, page, BITMAP_PAGE_CLEAN); @@ -1132,6 +1142,8 @@ void bitmap_daemon_work(struct bitmap *b } } + if (bitmap->allclean == 0) + bitmap->mddev->thread->timeout = bitmap->daemon_sleep * HZ; } static bitmap_counter_t *bitmap_get_counter(struct bitmap *bitmap, @@ -1226,6 +1238,7 @@ int bitmap_startwrite(struct bitmap *bit sectors -= blocks; else sectors = 0; } + bitmap->allclean = 0; return 0; } @@ -1296,6 +1309,7 @@ int bitmap_start_sync(struct bitmap *bit } } spin_unlock_irq(&bitmap->lock); + bitmap->allclean = 0; return rv; } @@ -1332,6 +1346,7 @@ void bitmap_end_sync(struct bitmap *bitm } unlock: spin_unlock_irqrestore(&bitmap->lock, flags); + bitmap->allclean = 0; } void bitmap_close_sync(struct bitmap *bitmap) @@ -1399,7 +1414,7 @@ static void bitmap_set_memory_bits(struc set_page_attr(bitmap, page, BITMAP_PAGE_CLEAN); } spin_unlock_irq(&bitmap->lock); - + bitmap->allclean = 0; } /* dirty the memory and file bits for bitmap chunks "s" to "e" */ diff .prev/include/linux/raid/bitmap.h ./include/linux/raid/bitmap.h --- .prev/include/linux/raid/bitmap.h 2008-02-22 15:45:56.000000000 +1100 +++ ./include/linux/raid/bitmap.h 2008-02-22 15:45:56.000000000 +1100 @@ -235,6 +235,8 @@ struct bitmap { unsigned long flags; + int allclean; + unsigned long max_write_behind; /* write-behind mode */ atomic_t behind_writes;