linux-kernel - Re: [PATCH 1/1] mmc: Set optimal I/O size when mmc_setip

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Date:   Sun, 27 Aug 2023 00:26:35 +0800
From:   <Sharp.Xia@...iatek.com>
To:     <shawn.lin@...k-chips.com>
CC:     <Sharp.Xia@...iatek.com>,
        <angelogioacchino.delregno@...labora.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-mediatek@...ts.infradead.org>, <linux-mmc@...r.kernel.org>,
        <matthias.bgg@...il.com>, <ulf.hansson@...aro.org>,
        <wsd_upstream@...iatek.com>
Subject: Re: [PATCH 1/1] mmc: Set optimal I/O size when mmc_setip_queue

On Fri, 2023-08-25 at 17:17 +0800, Shawn Lin wrote:
>  	 
> 
>  On 2023/8/25 16:39, Sharp.Xia@...iatek.com wrote:
> > On Fri, 2023-08-25 at 16:11 +0800, Shawn Lin wrote:
> >>   
> >>   Hi Sharp,
> 
> ...
> 
> >>> 1024
> >>>
> > Hi Shawn,
> > 
> > What is your readahead value before and after applying this patch?
> > 
> 
> The original readahead is 128, and after applying the patch is 1024
> 
> 
> cat /d/mmc0/ios
> clock:          200000000 Hz
> actual clock:   200000000 Hz
> vdd:            18 (3.0 ~ 3.1 V)
> bus mode:       2 (push-pull)
> chip select:    0 (don't care)
> power mode:     2 (on)
> bus width:      3 (8 bits)
> timing spec:    10 (mmc HS400 enhanced strobe)
> signal voltage: 1 (1.80 V)
> driver type:    0 (driver type B)
> 
> The driver I used is sdhci-of-dwcmshc.c with a KLMBG2JETDB041 eMMC
> chip.

I tested with RK3568 and sdhci-of-dwcmshc.c driver, the performance improved by 2~3%.
 
Before:
root@...nWrt:/mnt/mmcblk0p3# time dd if=test.img of=/dev/null
2097152+0 records in
2097152+0 records out
real    0m 6.01s
user    0m 0.84s
sys     0m 2.89s
root@...nWrt:/mnt/mmcblk0p3# cat /sys/block/mmcblk0/queue/read_ahead_kb
128
 
After:
root@...nWrt:/mnt/mmcblk0p3# echo 3 > /proc/sys/vm/drop_caches
root@...nWrt:/mnt/mmcblk0p3# time dd if=test.img of=/dev/null
2097152+0 records in
2097152+0 records out
real    0m 5.86s
user    0m 1.04s
sys     0m 3.18s
root@...nWrt:/mnt/mmcblk0p3# cat /sys/block/mmcblk0/queue/read_ahead_kb
1024
 
root@...nWrt:/sys/kernel/debug/mmc0# cat ios
clock:          200000000 Hz
actual clock:   200000000 Hz
vdd:            18 (3.0 ~ 3.1 V)
bus mode:       2 (push-pull)
chip select:    0 (don't care)
power mode:     2 (on)
bus width:      3 (8 bits)
timing spec:    9 (mmc HS200)
signal voltage: 1 (1.80 V)
driver type:    0 (driver type B)