netdev - Re: cat /proc/net/tcp takes 0.5 seconds on x86

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Message-ID: <48B5E6A3.6@cosmosbay.com>
Date:	Thu, 28 Aug 2008 01:43:31 +0200
From:	Eric Dumazet <dada1@...mosbay.com>
To:	David Miller <davem@...emloft.net>
Cc:	andi@...stfloor.org, davej@...hat.com, netdev@...r.kernel.org,
	j.w.r.degoede@....nl
Subject: Re: cat /proc/net/tcp takes 0.5 seconds on x86_64

David Miller a écrit :
> From: Eric Dumazet <dada1@...mosbay.com>
> Date: Thu, 28 Aug 2008 01:09:19 +0200
> 
>> Not really, I suspect commit (a7ab4b501f9b8a9dc4d5cee542db67b6ccd1088b [TCPv4]: Improve BH latency in /proc/net/tcp) is responsible for longer delays.
>> Note that its rather old :
>  ...
>> We used to disable bh once, while reading the table. This sucked.
>>
>> In case machine is handling trafic, we now are preemptable by softirqs
>> while reading /proc/net/tcp. Thats a good thing.
> 
> Yes, that would account for it, good spotting.
> 
>> By the way, I find Andi patch usefull. Same thing could be done for /proc/net/rt_cache.
> 
> Fair enough.  If you can cook up a quick rt_cache patch I'll toss it and
> Andi's patch into net-next so it can cook for a while.

Well, first patch I would like to submit is about letting netlink being able to be 
faster than /proc/net/tcp again :)

Thank you

[PATCH] tcp: speedup tcp hash table lookups for NETLINK

Avoid taking locks for empty buckets.

Signed-off-by: Eric Dumazet <dada1@...mosbay.com>


View attachment "inet_diag.patch" of type "text/plain" (561 bytes)