Messages in this thread | | | Subject | Re: Serious performance degradation on a RAID with kernel 2.6.10-bk7 and later | From | Nick Piggin <> | Date | Thu, 21 Apr 2005 11:11:51 +1000 |
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On Wed, 2005-04-20 at 10:55 -0600, jmerkey wrote: > > For 3Ware, you need to chage the queue depths, and you will see > dramatically improved performance. 3Ware can take requests > a lot faster than Linux pushes them out. Try changing this instead, you > won't be going to sleep all the time waiting on the read/write > request queues to get "unstarved". > > > /linux/include/linux/blkdev.h > > //#define BLKDEV_MIN_RQ 4 > //#define BLKDEV_MAX_RQ 128 /* Default maximum */ > #define BLKDEV_MIN_RQ 4096 > #define BLKDEV_MAX_RQ 8192 /* Default maximum */ >
BTW, don't do this. BLKDEV_MIN_RQ sets the size of the mempool reserved requests and will only get slightly used in low memory conditions, so most memory will probably be wasted.
Just change /sys/block/xxx/queue/nr_requests
Nick
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