Re: 24 lost ticks with 2.6.20.10 kernel

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Chuck Ebbert wrote:
Kok, Auke wrote:
Michel Lespinasse wrote:
(I've added the E1000 maintainers to the thread as I found the issue
seems to go away after I compile out that driver. For reference, I was
trying to figure out why I lose exactly 24 ticks about every two
seconds, as shown with report_lost_ticks. This is with a DQ965GF
motherboard with onboard E1000).
that's perfectly likely. The main issue is that we read the hardware
stats every two seconds and that can consume quite some time. It's
strange that you are losing that many ticks IMHO, but losing one or two
might very well be.

We've been playing with all sorts of solutions to this problem and
haven't come up with a way to reduce the load of the system reading HW
stats, and it remains the most likely culprit, allthough I don't rule
out clean routines just yet. This could very well be exaggerated at
100mbit speeds as well, I never looked at that.

I've had good results with 2.6.21.1 (even running tickless :)) on these
NICs. Have you tried that yet?

Maybe this could fix it in 2.6.20? (went into 2.6.21)

well, that hasn't got anything to do with stats, but is part of the clean_tx/rx codepath. I personally don't get any lost_ticks so I can't reproduce, but that was why I was hinting that you can try it for us ;)

codewise, the patch below makes our cleanup routine spend _more_ time, instead of less, which is why I think it's not the cause nor fix.

Auke


--------------------------------------------------------------------------

Gitweb:     http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=46fcc86dd71d70211e965102fb69414c90381880
Commit:     46fcc86dd71d70211e965102fb69414c90381880
Parent:     2b858bd02ffca71391161f5709588fc70da79531
Author:     Linus Torvalds <[email protected]>
AuthorDate: Thu Apr 19 18:21:01 2007 -0700
Committer:  Linus Torvalds <[email protected]>
CommitDate: Thu Apr 19 18:21:01 2007 -0700

    Revert "e1000: fix NAPI performance on 4-port adapters"
This reverts commit 60cba200f11b6f90f35634c5cd608773ae3721b7. It's been
    linked to lockups of the e1000 hardware, see for example
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=229603 but it's likely that the commit itself is not really introducing the
    bug, but just allowing an unrelated problem to rear its ugly head (ie
    one current working theory is that the code exposes us to a hardware
    race condition by decreasing the amount of time we spend in each NAPI
    poll cycle).
We'll revert it until root cause is known. Intel has a repeatable
    reproduction on two different machines and bus traces of the hardware
    doing something bad.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

[Index of Archives]     [Kernel Newbies]     [Netfilter]     [Bugtraq]     [Photo]     [Stuff]     [Gimp]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Video 4 Linux]     [Linux for the blind]     [Linux Resources]
  Powered by Linux