From mboxrd@z Thu Jan 1 00:00:00 1970 From: NeilBrown Subject: [md PATCH 2/3] md: bitmap: improve bitmap maintenance code. Date: Mon, 25 May 2009 14:33:52 +1000 Message-ID: <20090525043352.3758.44520.stgit@notabene.brown> References: <20090525042538.3758.7928.stgit@notabene.brown> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20090525042538.3758.7928.stgit@notabene.brown> Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org Cc: NeilBrown List-Id: linux-raid.ids The code for checking which bits in the bitmap can be cleared has 2 problems: 1/ it repeatedly takes and drops a spinlock, where it would make more sense to just hold on to it most of the time. 2/ it doesn't make use of some opportunities to skip large sections of the bitmap This patch fixes those. It will only affect CPU consumption, not correctness. Signed-off-by: NeilBrown --- drivers/md/bitmap.c | 13 +++++++------ 1 files changed, 7 insertions(+), 6 deletions(-) diff --git a/drivers/md/bitmap.c b/drivers/md/bitmap.c index 47c68bc..56df1ce 100644 --- a/drivers/md/bitmap.c +++ b/drivers/md/bitmap.c @@ -1097,14 +1097,12 @@ void bitmap_daemon_work(struct bitmap *bitmap) } bitmap->allclean = 1; + spin_lock_irqsave(&bitmap->lock, flags); for (j = 0; j < bitmap->chunks; j++) { bitmap_counter_t *bmc; - spin_lock_irqsave(&bitmap->lock, flags); - if (!bitmap->filemap) { + if (!bitmap->filemap) /* error or shutdown */ - spin_unlock_irqrestore(&bitmap->lock, flags); break; - } page = filemap_get_page(bitmap, j); @@ -1121,6 +1119,8 @@ void bitmap_daemon_work(struct bitmap *bitmap) write_page(bitmap, page, 0); bitmap->allclean = 0; } + spin_lock_irqsave(&bitmap->lock, flags); + j |= (PAGE_BITS - 1); continue; } @@ -1181,9 +1181,10 @@ void bitmap_daemon_work(struct bitmap *bitmap) ext2_clear_bit(file_page_offset(j), paddr); kunmap_atomic(paddr, KM_USER0); } - } - spin_unlock_irqrestore(&bitmap->lock, flags); + } else + j |= PAGE_COUNTER_MASK; } + spin_unlock_irqrestore(&bitmap->lock, flags); /* now sync the final page */ if (lastpage != NULL) {