Messages in this thread | | | Subject | Re: [PATCH] Speed up the cdrw packet writing driver | From | Lee Revell <> | Date | Tue, 24 Aug 2004 17:57:01 -0400 |
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On Tue, 2004-08-24 at 17:47, Andrew Morton wrote: > Peter Osterlund <petero2@telia.com> wrote: > > > > Why is it not nice? If the VM has decided to create 400MB of dirty > > data on a DVD+RW packet device, I don't see a problem with submitting > > all bio's at the same time to the packet device. > > We also have a limit on the number of in-flight requests: > /sys/block/sda/queue/nr_requests. It defaults to 128. > > Are you saying that your requests are so huge that each one has 1000 BIOs? > That would be odd, for an IDE interface. >
This defaults to 8192 on my (IDE) system. IIRC this value is larger if 48-bit addressing is in use (drive size > ~128GB). It does not seem right to me that the size of your hard drive should dictate the amount of I/O allowed to be in flight.
Lee
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