Re: generic_make_request fucntion for scsi_disk

From: Alan Stern
Date: Sat Jun 20 2009 - 10:56:26 EST

You should use Reply-To-All so that other people reading the mailing
list will be able to follow and contribute to the thread.

On Sat, 20 Jun 2009, Ravish Tayal wrote:

> Thanks Alan,
> I am actually trying to profile the time taken by each layer to complete the
> disk write opertaion as sys_write to queue_command invokation veries alot.

Of course it varies. The kernel buffers disk writes, shuffles them
around, and then carries them out when it wants to. As James has
pointed out, your write(2) system calls don't directly cause any I/O to
take place.

Alan Stern

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