Re: System unresponsitive when copying HD/HD

From: Alan Cox (
Date: Sun Feb 04 2001 - 06:01:27 EST

> If I have vmstat running, I notice blocks trickling out to the disk, 5sec averages
> 495,142,151,155,136,257,15,0. Note that the maximum read rate (hdparm -t) of this
> disk is in the 12-14M/s range. I'm getting about 1-5% of that on output with the
> system's disk subsystem being apparently unable to do anything else.
> This is with IDE hard disk with DMA enabled.
> a) is this expected performance on a large linear write?


> b) should I expect other disk operations to be denied service as long as
> the write is 'flushing'?


But try 2.4.1 before worrying too much. That fixed a lot of the block
performance problems I was seeing (2.4.1 ruins the VM performance under paging
loads but the I/O speed is fixed ;))

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