linux-kernel - Re: [PATCH AUTOSEL 4.9 08/10] Revert "usb: storage: Add quirk for Samsung Fit flash"

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Message-ID: <20221017124632.GA13227@duo.ucw.cz>
Date:   Mon, 17 Oct 2022 14:46:32 +0200
From:   Pavel Machek <pavel@...x.de>
To:     Sasha Levin <sashal@...nel.org>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        sunghwan jung <onenowy@...il.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stern@...land.harvard.edu, linux-usb@...r.kernel.org,
        usb-storage@...ts.one-eyed-alien.net
Subject: Re: [PATCH AUTOSEL 4.9 08/10] Revert "usb: storage: Add quirk for
 Samsung Fit flash"

Hi!

> From: sunghwan jung <onenowy@...il.com>
> 
> [ Upstream commit ad5dbfc123e6ffbbde194e2a4603323e09f741ee ]
> 
> This reverts commit 86d92f5465958752481269348d474414dccb1552,
> which fix the timeout issue for "Samsung Fit Flash".
> 
> But the commit affects not only "Samsung Fit Flash" but also other usb
> storages that use the same controller and causes severe performance
> regression.
> 
>  # hdparm -t /dev/sda (without the quirk)
>  Timing buffered disk reads: 622 MB in  3.01 seconds = 206.66 MB/sec
> 
>  # hdparm -t /dev/sda (with the quirk)
>  Timing buffered disk reads: 220 MB in  3.00 seconds =  73.32 MB/sec
> 
> The commit author mentioned that "Issue was reproduced after device has
> bad block", so this quirk should be applied when we have the timeout
> issue with a device that has bad blocks.
> 
> We revert the commit so that we apply this quirk by adding kernel
> paramters using a bootloader or other ways when we really need it,
> without the performance regression with devices that don't have the
> issue.

Re-introducing timeouts for users in middle of stable series... may
not be nice. Is there better fix in a follow up to this that was not
backported?

I see that buffered reads got faster, but that may not really mean
real performance gains...

Best regards,
								Pavel

>  drivers/usb/storage/unusual_devs.h | 6 ------
>  1 file changed, 6 deletions(-)
> 
> diff --git a/drivers/usb/storage/unusual_devs.h b/drivers/usb/storage/unusual_devs.h
> index 5a6ca1460711..8c51bb66f16f 100644
> --- a/drivers/usb/storage/unusual_devs.h
> +++ b/drivers/usb/storage/unusual_devs.h
> @@ -1294,12 +1294,6 @@ UNUSUAL_DEV( 0x090a, 0x1200, 0x0000, 0x9999,
>  		USB_SC_RBC, USB_PR_BULK, NULL,
>  		0 ),
>  
> -UNUSUAL_DEV(0x090c, 0x1000, 0x1100, 0x1100,
> -		"Samsung",
> -		"Flash Drive FIT",
> -		USB_SC_DEVICE, USB_PR_DEVICE, NULL,
> -		US_FL_MAX_SECTORS_64),
> -
>  /* aeb */
>  UNUSUAL_DEV( 0x090c, 0x1132, 0x0000, 0xffff,
>  		"Feiya",

-- 
DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany

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