From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37576) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1a0nMk-0003Ck-Vd for qemu-devel@nongnu.org; Mon, 23 Nov 2015 04:24:55 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1a0nMj-00065u-VM for qemu-devel@nongnu.org; Mon, 23 Nov 2015 04:24:54 -0500 References: <1448013593-14282-1-git-send-email-famz@redhat.com> <1448013593-14282-2-git-send-email-famz@redhat.com> <5652D602.8010809@cn.fujitsu.com> <20151123091911.GB689@ad.usersys.redhat.com> From: Wen Congyang Message-ID: <5652DB34.5090300@cn.fujitsu.com> Date: Mon, 23 Nov 2015 17:24:04 +0800 MIME-Version: 1.0 In-Reply-To: <20151123091911.GB689@ad.usersys.redhat.com> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH for 2.6 1/3] backup: Use Bitmap to replace "s->bitmap" List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Fam Zheng Cc: Kevin Wolf , vsementsov@virtuozzo.com, qemu-block@nongnu.org, Jeff Cody , qemu-devel@nongnu.org, mreitz@redhat.com, pbonzini@redhat.com, jsnow@redhat.com On 11/23/2015 05:19 PM, Fam Zheng wrote: > On Mon, 11/23 17:01, Wen Congyang wrote: >> On 11/20/2015 05:59 PM, Fam Zheng wrote: >>> "s->bitmap" tracks done sectors, we only check bit states without using any >>> iterator which HBitmap is good for. Switch to "Bitmap" which is simpler and >>> more memory efficient. >>> >>> Meanwhile, rename it to done_bitmap, to reflect the intention. >>> >>> Signed-off-by: Fam Zheng >>> --- >>> block/backup.c | 11 ++++++----- >>> 1 file changed, 6 insertions(+), 5 deletions(-) >>> >>> diff --git a/block/backup.c b/block/backup.c >>> index 3b39119..d408f98 100644 >>> --- a/block/backup.c >>> +++ b/block/backup.c >>> @@ -22,6 +22,7 @@ >>> #include "qapi/qmp/qerror.h" >>> #include "qemu/ratelimit.h" >>> #include "sysemu/block-backend.h" >>> +#include "qemu/bitmap.h" >>> >>> #define BACKUP_CLUSTER_BITS 16 >>> #define BACKUP_CLUSTER_SIZE (1 << BACKUP_CLUSTER_BITS) >>> @@ -47,7 +48,7 @@ typedef struct BackupBlockJob { >>> BlockdevOnError on_target_error; >>> CoRwlock flush_rwlock; >>> uint64_t sectors_read; >>> - HBitmap *bitmap; >>> + unsigned long *done_bitmap; >>> QLIST_HEAD(, CowRequest) inflight_reqs; >>> } BackupBlockJob; >>> >>> @@ -113,7 +114,7 @@ static int coroutine_fn backup_do_cow(BlockDriverState *bs, >>> cow_request_begin(&cow_request, job, start, end); >>> >>> for (; start < end; start++) { >>> - if (hbitmap_get(job->bitmap, start)) { >>> + if (test_bit(start, job->done_bitmap)) { >>> trace_backup_do_cow_skip(job, start); >>> continue; /* already copied */ >>> } >>> @@ -164,7 +165,7 @@ static int coroutine_fn backup_do_cow(BlockDriverState *bs, >>> goto out; >>> } >>> >>> - hbitmap_set(job->bitmap, start, 1); >>> + bitmap_set(job->done_bitmap, start, 1); >> >> You can use set_bit() here. > > Why? I think bitmap_set is a better match with bitmap_new below. set_bit() is quicker than bitmap_set() if you only set one bit. Thanks Wen Congyang > > Fam > >> >> Thanks >> Wen Congyang >> >>> >>> /* Publish progress, guest I/O counts as progress too. Note that the >>> * offset field is an opaque progress value, it is not a disk offset. >>> @@ -394,7 +395,7 @@ static void coroutine_fn backup_run(void *opaque) >>> start = 0; >>> end = DIV_ROUND_UP(job->common.len, BACKUP_CLUSTER_SIZE); >>> >>> - job->bitmap = hbitmap_alloc(end, 0); >>> + job->done_bitmap = bitmap_new(end); >>> >>> bdrv_set_enable_write_cache(target, true); >>> if (target->blk) { >>> @@ -475,7 +476,7 @@ static void coroutine_fn backup_run(void *opaque) >>> /* wait until pending backup_do_cow() calls have completed */ >>> qemu_co_rwlock_wrlock(&job->flush_rwlock); >>> qemu_co_rwlock_unlock(&job->flush_rwlock); >>> - hbitmap_free(job->bitmap); >>> + g_free(job->done_bitmap); >>> >>> if (target->blk) { >>> blk_iostatus_disable(target->blk); >>> >> > . >