RE: [RFC PATCH] mmc: core: Disable REQ_FUA if the eMMC supports an internal cache

["Christian Löhle" <CLoehle@hyperstone.com>]

I have benchmarked the FUA/Cache behavior a bit.
I don't have an actual filesystem benchmark that does what I wanted and is easy to port to the target so I used:

# call with
# for loop in {1..3}; do sudo dd if=/dev/urandom bs=1M of=/dev/mmcblk2; done; for loop in {1..5}; do time ./filesystembenchmark.sh; umount /mnt; done
mkfs.ext4 -F /dev/mmcblk2
mount /dev/mmcblk2 /mnt
for i in {1..3}
do
cp -r linux-6.2.2 /mnt/$i
done
for i in {1..3}
do
rm -r /mnt/$i
done
for i in {1..3}
do
cp -r linux-6.2.2 /mnt/$i
done


I found a couple of DUTs that I can link, I also tested one industrial card.

DUT1: blue PCB Foresee eMMC
https://pine64.com/product/32gb-emmc-module/
DUT2: green PCB SiliconGo eMMC
Couldn't find that one online anymore unfortunately
DUT3: orange hardkernel PCB 8GB
https://www.hardkernel.com/shop/8gb-emmc-module-c2-android/
DUT4: orange hardkernel PCB white dot
https://rlx.sk/en/odroid/3198-16gb-emmc-50-module-xu3-android-for-odroid-xu3.html
DUT5: Industrial card


The test issued 461 DO_REL_WR during one of the iterations for DUT5

DUT1:
Cache, no FUA:
13:04.49
13:13.82
13:30.59
13:28:13
13:20:64
FUA:
13:30.32
13:36.26
13:10.86
13:32.52
13:48.59

DUT2:
FUA:
8:11.24
7:47.73
7:48.00
7:48.18
7:47.38
Cache, no FUA:
8:10.30
7:48.97
7:48.47
7:47.93
7:44.18

DUT3:
Cache, no FUA:
7:02.82
6:58.94
7:03.20
7:00.27
7:00.88
FUA:
7:05.43
7:03.44
7:04.82
7:03.26
7:04.74

DUT4:
FUA:
7:23.92
7:20.15
7:20.52
7:19.10
7:20.71
Cache, no FUA:
7:20.23
7:20.48
7:19.94
7:18.90
7:19.88

Cache, no FUA:
7:19.36
7:02.11
7:01.53
7:01.35
7:00.37
Cache, no FUA CQE:
7:17.55
7:00.73
6:59.25
6:58.44
6:58.60
FUA:
7:15.10
6:58.99
6:58.94
6:59.17
6:60.00
FUA CQE:
7:11.03
6:58.04
6:56.89
6:56.43
6:56:28

If anyone has any comments or disagrees with the benchmark, or has a specific eMMC to test, let me know.

Regards,
Christian

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