Re: [PATCH -mm] make swapin readahead skip over holes

From: John Stoffel
Date: Wed Jan 11 2012 - 16:04:34 EST


>>>>> "Christoph" == Christoph Lameter <cl@xxxxxxxxx> writes:

Christoph> On Wed, 11 Jan 2012, John Stoffel wrote:
KOSAKI> so, we can eat free lunch up to 7MB ~= 60(MB/sec) * 1000 / 8.5(ms).
>>
>> What if the disk is busy doing other writeout or readin during this
>> time? You can't assume you have the full disk bandwidth available,
>> esp when you hit a swap storm like this.

Christoph> The assumptions by Kosaki are quite conservative.

Just checking

Christoph> What if one did not get a disk from the garbage heap but
Christoph> instead has a state of the art storage cluster or simply an
Christoph> SSD (in particular relevant now since HDs are in short
Christoph> supply given the situation in Asia)?

I don't know, I was just trying to make sure he thinks about disks
which are slower than he expects, since there are lots of them still
out there.

John

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