RE: Poor write performance to boot area using rcar-gen3-sdhi

[Christian Loehle <CLoehle@hyperstone.com>]

Your eMMC likely treats the boot partitions differently than the user area, e.g. in regards to cache.
Is this reproducible for more 4k writes? What about larger writes?
The eMMC might not even have the mapping available after boot and first has to internally switch to it, in contrast to at u-boot stage?

Anyway this is probably more a question to your eMMC manufacturer and nothing the host is to be blamed, as you mentioned yourself, the time is spent at CMD25.

-----Original Message-----
From: Richard Weinberger <richard@nod.at> 
Sent: Tuesday, April 18, 2023 8:16 AM
To: Biju Das <biju.das.jz@bp.renesas.com>
Cc: linux-mmc <linux-mmc@vger.kernel.org>; linux-renesas-soc <linux-renesas-soc@vger.kernel.org>; wsa+renesas <wsa+renesas@sang-engineering.com>; ulf hansson <ulf.hansson@linaro.org>
Subject: Re: Poor write performance to boot area using rcar-gen3-sdhi

----- Ursprüngliche Mail -----
> Von: "Biju Das" <biju.das.jz@bp.renesas.com> Not sure, the file system 
> used between /dev/mmcblk1boot1 and /dev/mmcblk1p13 is making 
> difference at Linux?
> 
> I have seen performance difference between FAT and ext4.

There is no filesystem, I'm writing directly using dd to the raw block device.

Thanks,
//richard

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