netdev - Re: [PATCH net] rhashtable: use cond

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Message-ID: <54EF40B7.8060903@iogearbox.net>
Date:	Thu, 26 Feb 2015 16:50:15 +0100
From:	Daniel Borkmann <daniel@...earbox.net>
To:	Eric Dumazet <eric.dumazet@...il.com>,
	Patrick McHardy <kaber@...sh.net>
CC:	Alexei Starovoitov <alexei.starovoitov@...il.com>,
	David Laight <David.Laight@...lab.com>,
	"davem@...emloft.net" <davem@...emloft.net>,
	"tgraf@...g.ch" <tgraf@...g.ch>,
	"pablo@...filter.org" <pablo@...filter.org>,
	"johunt@...mai.com" <johunt@...mai.com>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH net] rhashtable: use cond_resched()

On 02/26/2015 04:20 PM, Eric Dumazet wrote:
> From: Eric Dumazet <edumazet@...gle.com>
>
> If a hash table has 128 slots and 16384 elems, expand to 256 slots
> takes more than one second. For larger sets, a soft lockup is detected.
>
> Holding cpu for that long, even in a work queue is a show stopper
> for non preemptable kernels.
>
> cond_resched() at strategic points to allow process scheduler
> to reschedule us.
>
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>

Acked-by: Daniel Borkmann <daniel@...earbox.net>
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