Re: USB 2.0 with 250Gb disk and insane loads

Terje Malmedal (terje.malmedal@usit.uio.no)
Tue, 3 Jun 2003 13:49:26 +0200


[Alexander Hoogerhuis]
> Stuck it in an older machine on USB 1.1 and it foudn the disk fine
> (redhat 9, 2.4.20-13.9 kernel on that machine), and ditto result:

> 19:15:16 up 2 days, 20:23, 4 users, load average: 6.02, 2.41, 0.89
> 58 processes: 55 sleeping, 3 running, 0 zombie, 0 stopped
> CPU states: 0.2% user 4.0% system 0.0% nice 0.0% iowait 95.8% idle
> Mem: 385040k av, 380820k used, 4220k free, 0k shrd, 67368k buff
> 224720k active, 69412k inactive
> Swap: 521632k av, 80k used, 521552k free 237452k cached

> and generating about 2500 interrupts for the usb controller per 10
> seconds and when i finally break it off and give it "sync" it uses
> about two minutes with about 4500 per 10 seconds to get it all on
> disk. On 2.4 the machine becomes more and more sluggish if I let it
> go more than a short minute.

I had the same problem with USB 1.1. I solved it by writing a
LD_PRELOAD-able shared library which overrides write() to do a
fdatasync() on the filehandle after a megabyte worth of writes.

Would be nice to have it fixed in the kernel though.

-- 
 - Terje
malmedal@usit.uio.no
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