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From: "Martin K. Petersen" <>
To: "Martin K. Petersen" <>
Cc: Jens Axboe <>,
	Damien Le Moal <>,
	Mike Snitzer <>,
	"" <>,
	"" <>,
	"" <>,
	Keith Busch <>
Subject: Re: [PATCH] block: Improve io_opt limit stacking
Date: Fri, 22 May 2020 09:36:18 -0400
Message-ID: <> (raw)
In-Reply-To: <> (Martin K. Petersen's message of "Fri, 22 May 2020 09:28:36 -0400")

>>> +	if (t->io_opt & (t->physical_block_size - 1))
>>> +		t->io_opt = lcm(t->io_opt, t->physical_block_size);
>> Any comment on this patch ?  Note: the patch the patch "nvme: Fix
>> io_opt limit setting" is already queued for 5.8.
> Setting io_opt to the physical block size is not correct.

Oh, missed the lcm(). But I'm still concerned about twiddling io_opt to
a value different than the one reported by an underlying device.

Setting io_opt to something that's less than a full stripe width in a
RAID, for instance, doesn't produce the expected result. So I think I'd
prefer not to set io_opt at all if it isn't consistent across all the
stacked devices.

Let me chew on it for a bit...

Martin K. Petersen	Oracle Linux Engineering

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Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-14  6:58 Damien Le Moal
2020-05-22  7:27 ` Damien Le Moal
2020-05-22 13:28   ` Martin K. Petersen
2020-05-22 13:36     ` Martin K. Petersen [this message]
2020-05-22 14:14       ` Keith Busch

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