Cc'ing qemu-block. Dou Liyang <douly.f...@cn.fujitsu.com> writes:
> Change log v3 -> v4: > 1. Develop these into the non-RFC patches. > 2. Fix some comments. > 3. do declarations first. > > Change log v2 -> v3: > 1. Remove the unnecessary code for the bdrv_next_node(). > 2. Remove the change of the locking rules. > Even if this change can improve the performance, but it may > effect the consistency. > > The Qemu uses the qmp_query_blockstats() function to get the > blockstats. As the function has been changed several times, it > becomes more complex and longer. > > For the multi-disks guest, if we want to execute I/O operations > and this function at the same time. we can use the dataplane > feature to hold I/O performance does not drop. But, Normally > without this feature, How to reduce the decline in performance? > > These patches refactor the qmp_query_blockstats() to make the > code easier to follow, and shorter as follows: > > From: > > +--------------+ +---------------------+ > | 1 | | 4. | > |next_query_bds| |bdrv_query_bds_stats +---+ > | | | | | > +--------^-----+ +-------------^-------+ | > | | | > +---------+----------+ +--------+-------+ | > | 0. | | 2. | | > |qmp_query_blockstats+------>bdrv_query_stats<---- > | | | | > +--------------------+ +--------+-------+ > | > +-------------v-------+ > | 3. | > |bdrv_query_blk_stats | > | | > +---------------------+ > > To: > > +--------------+ > | | > +--------v-----------+ | > +---> 3. | | > +-------------------+ | |bdrv_query_bds_stats+--+ > | 1. +--+ | | > | + +--------------------+ > |qmp_query_blockstats--+ > | | | > +-------------------+ | +--------------------+ > | | 2. | > +---> | > |bdrv_query_blk_stats| > | | > +--------------------+ > > > They also optimize the fuction by reducing its running time. > > 1. The function running time > > the time it takes(ns) in each requests: > the disk numbers | 10 | 500 > ------------------------------------- > before these patches | 19429 | 667722 > after these patches | 18536 | 627945 > > 2. For the performance > used the dd command likes this to test: > dd if=date_1.dat of=date_2.dat conv=fsync oflag=direct bs=1k count=100k. > > the I/O performance is degraded(%) during the monitor: > the disk numbers | 10 | 500 > ------------------------------------- > before these patches | 1.3 | 14.2 > after these patches | 1.0 | 11.3 Series Reviewed-by: Markus Armbruster <arm...@redhat.com>
