Re: [PATCH] tcp_cubic: limit delayed_ack ratio to prevent divideerror

From: TB
Date: Fri May 06 2011 - 12:15:29 EST


-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On 11-05-04 04:53 PM, Brandeburg, Jesse wrote:
>
>
> On Wed, 4 May 2011, Stephen Hemminger wrote:
>
>> TCP Cubic keeps a metric that estimates the amount of delayed
>> acknowledgements to use in adjusting the window. If an abnormally
>> large number of packets are acknowledged at once, then the update
>> could wrap and reach zero. This kind of ACK could only
>> happen when there was a large window and huge number of
>> ACK's were lost.
>>
>> This patch limits the value of delayed ack ratio. The choice of 32
>> is just a conservative value since normally it should be range of
>> 1 to 4 packets.
>>
>> Signed-off-by: Stephen Hemminger <shemminger@xxxxxxxxxx>
>
> patch seems fine, but please credit the reporter (lkml@xxxxxxxxxxxx) with
> reporting the issue with logs, maybe even with Reported-by: and some kind
> of reference to the panic message or the email thread in the text or
> header?

We're currently testing the patch on 6 production servers

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.10 (GNU/Linux)
Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/

iQEcBAEBAgAGBQJNxB6yAAoJENOh8x1aI8Ye4ocH/3+6gjWWppgOwql0J4XGGD5R
wJX+u8A+YK2V+GBvxFgQs/qNa3IB/nnWwELolflO80twq2JrOq1I6g2n1VJhHjX4
b5jyROMe2gPHRKESibi84gNIuoImq4bqM/S1u7xWzcikTh8FxCevYQXTNilIKOOf
siuOIypFY7AyqSPjhq5/+HpTrrOQa097PAcVAr8RBO7niyrxAE75ACTolGAKBfvQ
HlOYKmxBT8SbnZ7YJNINopPdtpqz3iaraKWUoT44Wuv8Q8jt0cqB7YJWl0RG/C3y
ABK50Qihl1p6M+LL9jjR2YwVFkjiLyN3fO8g2pjVfn4wh0afFCyWtitN0OFd/4I=
=Vy5E
-----END PGP SIGNATURE-----
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/