Messages in this thread | | | Date | Sun, 5 Sep 1999 10:57:41 +0200 (MET DST) | From | Gerard Roudier <> | Subject | Re: Fixing the SCSI layer |
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On Sun, 5 Sep 1999, Alan Cox wrote:
> > Besides, cleaning up the code, has anyone identified specific performance > > problems that need to be fixed in the SCSI mid-layer? For some reason the > > Interphase FC adapter is topping out at ~72MB/s on sequential reads, > > this seems rather low, knowing that we can get 90+ with identical hardware > > under NT. > > The code is too heavy weight. I See performance limits with the Symbios > FC card too. In paticular the commands/second is very very limited.
Depends on the number of commands per seconds you need.
I can get up to 13000 actual 1K I/O READs per seconds on a single LVD BUS with useless kernel buffering under 2.0.36 using 2 fast disks and 2 reader processes (1 per device to overlap driver+controller+interrupt+etc... latencies). I just disable readahead for the block devices and read 1K chunck at a time. May-be I could get slightly more cmds/sec by eliminating kernel buffering (or under recent kernel), but I am too lazy to hack for that.
The machine is a PII/233 with 66MHz system bus and 33 MHz 32bit PCI BUS, controller can be a SYM53C896 or 895.
In my immediate opinion, it could well be some latency in some device, likely the controller, that makes the commands/second throughput not being as good as you expect.
Gérard.
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