Re: [PATCH 1/1] mmc: Set optimal I/O size when mmc_setip_queue

Sharp.Xia
2023-08-25T09:06:59Z

On Fri, 2023-08-25 at 16:11 +0800, Shawn Lin wrote:
>
> Hi Sharp,
>
> On 2023/8/25 15:10, Sharp Xia (夏宇彬) wrote:
> > On Thu, 2023-08-24 at 12:55 +0200, Ulf Hansson wrote:
> >>
> >> External email : Please do not click links or open attachments
> until
> >> you have verified the sender or the content.
> >> On Fri, 18 Aug 2023 at 04:45, <Sharp.Xia@mediatek.com> wrote:
> >>>
> >>> From: Sharp Xia <Sharp.Xia@mediatek.com>
> >>>
> >>> MMC does not set readahead and uses the default
> VM_READAHEAD_PAGES
> >>> resulting in slower reading speed.
> >>> Use the max_req_size reported by host driver to set the optimal
> >>> I/O size to improve performance.
> >>
> >> This seems reasonable to me. However, it would be nice if you
> could
> >> share some performance numbers too - comparing before and after
> >> $subject patch.
> >>
> >> Kind regards
> >> Uffe
> >>
> >>>
> >>> Signed-off-by: Sharp Xia <Sharp.Xia@mediatek.com>
> >>> ---
> >>> drivers/mmc/core/queue.c | 1 +
> >>> 1 file changed, 1 insertion(+)
> >>>
> >>> diff --git a/drivers/mmc/core/queue.c b/drivers/mmc/core/queue.c
> >>> index b396e3900717..fc83c4917360 100644
> >>> --- a/drivers/mmc/core/queue.c
> >>> +++ b/drivers/mmc/core/queue.c
> >>> @@ -359,6 +359,7 @@ static void mmc_setup_queue(struct mmc_queue
> >> *mq, struct mmc_card *card)
> >>> blk_queue_bounce_limit(mq->queue,
> BLK_BOUNCE_HIGH);
> >>> blk_queue_max_hw_sectors(mq->queue,
> >>> min(host->max_blk_count, host->max_req_size /
> >> 512));
> >>> + blk_queue_io_opt(mq->queue, host->max_req_size);
> >>> if (host->can_dma_map_merge)
> >>> WARN(!blk_queue_can_use_dma_map_merging(mq-
> >queue,
> >>> mmc_dev(
> hos
> >> t)),
> >>> --
> >>> 2.18.0
> >>>
> >
> > I test this patch on internal platform(kernel-5.15).
>
> I patched this one and the test shows me a stable 11% performance
> drop.
>
> Before:
> echo 3 > proc/sys/vm/drop_caches && dd if=/data/1GB.img of=/dev/null
>
> 2048000+0 records in
> 2048000+0 records out
> 1048576000 bytes (0.9 G) copied, 3.912249 s, 256 M/s
>
> After:
> echo 3 > proc/sys/vm/drop_caches && dd if=/data/1GB.img of=/dev/null
> 2048000+0 records in
> 2048000+0 records out
> 1048576000 bytes (0.9 G) copied, 4.436271 s, 225 M/s
>
> >
> > Before:
> > console:/ # echo 3 > /proc/sys/vm/drop_caches
> > console:/ # dd if=/mnt/media_rw/8031-130D/super.img of=/dev/null
> > 4485393+1 records in
> > 4485393+1 records out
> > 2296521564 bytes (2.1 G) copied, 37.124446 s, 59 M/s
> > console:/ # cat /sys/block/mmcblk0/queue/read_ahead_kb
> > 128
> >
> > After:
> > console:/ # echo 3 > /proc/sys/vm/drop_caches
> > console:/ # dd if=/mnt/media_rw/8031-130D/super.img of=/dev/null
> > 4485393+1 records in
> > 4485393+1 records out
> > 2296521564 bytes (2.1 G) copied, 28.956049 s, 76 M/s
> > console:/ # cat /sys/block/mmcblk0/queue/read_ahead_kb
> > 1024
> >
Hi Shawn,

What is your readahead value before and after applying this patch?