Re: amrd disk performance drop after running under high load

On Thu, 18 Oct 2007 15:57:16 -0600 Scott Long wrote:
Boris Samorodov wrote:

Since nobody answered so far, here is my two cents. I'm not an expert
here so it's only my imho.

On Wed, 17 Oct 2007 22:52:49 +0400 Alexey Popov wrote:

interrupt total rate
irq6: fdc0 8 0
irq14: ata0 47 0
irq16: uhci0 1428187319 1851
^^^^^^^^^^ ^^^^ [1]
irq18: uhci2 12374352 16
irq23: ehci0 3 0
irq46: amr0 11983237 15
irq64: em0 1427141755 1850
^^^^^^^^^^ ^^^^ [2]
cpu0: timer 1540896452 1997
cpu1: timer 1542377798 1999
Total 5962960971 7730

[1] and [2] looks suspicious to me (totals and rate are too close to
each other and btw to timers). Let the latter (timers) alone. Do you
use any USB device? Can you try to use other network card? That
behaviour seems to be an interrupt storm and/or irq collision.

It's neither. It's a side effect of a feature that FreeBSD abuses for
handling interrupts. Note that amr0 and ehci2 are acting similar. It's
mostly harmless, but it does waste CPU cycles. I wouldn't expect this
on a recent version of FreeBSD, though, at least not from the e1000
driver.

I see. Sorry for the noise. So, as I can understand _that_ can't be the
problem (as at subj) the OP is seeing?


WBR
--
bsam
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