Messages in this thread | | | Date | Fri, 21 Feb 2003 00:16:24 -0800 | From | Andrew Morton <> | Subject | Re: IO scheduler benchmarking |
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David Lang <david.lang@digitalinsight.com> wrote: > > one other useful test would be the time to copy a large (multi-gig) file. > currently this takes forever and uses very little fo the disk bandwidth, I > suspect that the AS would give more preference to reads and therefor would > go faster.
Yes, that's a test.
time (cp 1-gig-file foo ; sync)
2.5.62-mm2,AS: 1:22.36 2.5.62-mm2,CFQ: 1:25.54 2.5.62-mm2,deadline: 1:11.03 2.4.21-pre4: 1:07.69
Well gee.
> for a real-world example, mozilla downloads files to a temp directory and > then copies it to the premanent location. When I download a video from my > tivo it takes ~20 min to download a 1G video, during which time the system > is perfectly responsive, then after the download completes when mozilla > copies it to the real destination (on a seperate disk so it is a copy, not > just a move) the system becomes completely unresponsive to anything > requireing disk IO for several min.
Well 2.4 is unreponsive period. That's due to problems in the VM - processes which are trying to allocate memory get continually DoS'ed by `cp' in page reclaim.
For the reads-starved-by-writes problem which you describe, you'll see that quite a few of the tests did cover that. contest does as well.
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