* Disable aggregation of requests to a block device
@ 2009-02-19 12:08 Erez Zilber
0 siblings, 0 replies; only message in thread
From: Erez Zilber @ 2009-02-19 12:08 UTC (permalink / raw)
To: linux-kernel
Hi,
I'm running I/O to a block device (which is an iSCSI device, but that
shouldn't matter), usually with transfer length = 128kB. From time to
time, I see that 2 128kB commands get aggregated to a single 256kB
command, which is bad for me because the resources that I allocate are
based on 128kB commands. I could limit the command size by setting
/sys/block/sdX/queue/max_sectors_kb to 128kB, but sometimes I expect
larger commands (e.g. 512kB), and I don't want the block layer to
split them into smaller commands.
My question is: can I disable this aggregation? If yes, how? Else, is
there another solution?
Thanks,
Erez
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