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From: Richard Weinberger <richard@nod.at>
To: Miquel Raynal <miquel.raynal@bootlin.com>
Cc: "Michał Kępień" <kernel@kempniu.pl>,
	"Vignesh Raghavendra" <vigneshr@ti.com>,
	"Boris Brezillon" <boris.brezillon@collabora.com>,
	linux-mtd <linux-mtd@lists.infradead.org>,
	linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v3 4/4] mtdchar: add MEMREAD ioctl
Date: Thu, 3 Feb 2022 11:13:42 +0100 (CET)	[thread overview]
Message-ID: <340602071.12640.1643883222200.JavaMail.zimbra@nod.at> (raw)
In-Reply-To: <20220203104654.6cb43ea3@xps13>

----- Ursprüngliche Mail -----
> Von: "Miquel Raynal" <miquel.raynal@bootlin.com>
>> If mtd->erasesize is large (which is not uncommon these days) you might
>> request more from kmalloc() than it can serve.
>> Maybe kvmalloc() makes more sense?
> 
> Mmmh, I would really like these buffers dma-able.
> 
> I just discovered mtd_kmalloc_up_to(). Would this work?

mtd_kmalloc_up_to() makes sense to be more friendly to the system.
It tries to get memory without forcing write-back and such.
But if we're out of continuous memory it won't help much. 

Regarding dma-able, as soon you use something like UBI/UBIFS ontop of it
the mtd driver has to be able to deal in any way with vmalloc()'ed memory.

Another option would be not working on full erase blocks.

Thanks,
//richard

______________________________________________________
Linux MTD discussion mailing list
http://lists.infradead.org/mailman/listinfo/linux-mtd/

WARNING: multiple messages have this Message-ID (diff)
From: Richard Weinberger <richard@nod.at>
To: Miquel Raynal <miquel.raynal@bootlin.com>
Cc: "Michał Kępień" <kernel@kempniu.pl>,
	"Vignesh Raghavendra" <vigneshr@ti.com>,
	"Boris Brezillon" <boris.brezillon@collabora.com>,
	linux-mtd <linux-mtd@lists.infradead.org>,
	linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v3 4/4] mtdchar: add MEMREAD ioctl
Date: Thu, 3 Feb 2022 11:13:42 +0100 (CET)	[thread overview]
Message-ID: <340602071.12640.1643883222200.JavaMail.zimbra@nod.at> (raw)
In-Reply-To: <20220203104654.6cb43ea3@xps13>

----- Ursprüngliche Mail -----
> Von: "Miquel Raynal" <miquel.raynal@bootlin.com>
>> If mtd->erasesize is large (which is not uncommon these days) you might
>> request more from kmalloc() than it can serve.
>> Maybe kvmalloc() makes more sense?
> 
> Mmmh, I would really like these buffers dma-able.
> 
> I just discovered mtd_kmalloc_up_to(). Would this work?

mtd_kmalloc_up_to() makes sense to be more friendly to the system.
It tries to get memory without forcing write-back and such.
But if we're out of continuous memory it won't help much. 

Regarding dma-able, as soon you use something like UBI/UBIFS ontop of it
the mtd driver has to be able to deal in any way with vmalloc()'ed memory.

Another option would be not working on full erase blocks.

Thanks,
//richard

  reply	other threads:[~2022-02-03 10:14 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-01-25 10:48 [PATCH v3 0/4] mtdchar: add MEMREAD ioctl Michał Kępień
2022-01-25 10:48 ` Michał Kępień
2022-01-25 10:48 ` [PATCH v3 1/4] mtd: track maximum number of bitflips for each read request Michał Kępień
2022-01-25 10:48   ` Michał Kępień
2022-01-25 10:48 ` [PATCH v3 2/4] mtd: always initialize 'stats' in struct mtd_oob_ops Michał Kępień
2022-01-25 10:48   ` Michał Kępień
2022-01-25 10:48 ` [PATCH v3 3/4] mtd: add ECC error accounting for each read request Michał Kępień
2022-01-25 10:48   ` Michał Kępień
2022-01-25 10:48 ` [PATCH v3 4/4] mtdchar: add MEMREAD ioctl Michał Kępień
2022-01-25 10:48   ` Michał Kępień
2022-02-03  9:18   ` Richard Weinberger
2022-02-03  9:18     ` Richard Weinberger
2022-02-03  9:46     ` Miquel Raynal
2022-02-03  9:46       ` Miquel Raynal
2022-02-03 10:13       ` Richard Weinberger [this message]
2022-02-03 10:13         ` Richard Weinberger
2022-02-14 11:18         ` Michał Kępień
2022-02-14 11:18           ` Michał Kępień
2022-02-14 11:15     ` Michał Kępień
2022-02-14 11:15       ` Michał Kępień

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