netdev - Re: irq disable in __netdev_alloc

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Message-ID: <1414036276.2094.18.camel@edumazet-glaptop2.roam.corp.google.com>
Date:	Wed, 22 Oct 2014 20:51:16 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Alexander Duyck <alexander.duyck@...il.com>
Cc:	Alexei Starovoitov <ast@...mgrid.com>,
	Eric Dumazet <edumazet@...gle.com>,
	Network Development <netdev@...r.kernel.org>
Subject: Re: irq disable in __netdev_alloc_frag() ?

On Wed, 2014-10-22 at 20:19 -0700, Alexander Duyck wrote:

> Couldn't __netdev_alloc_frag() be forked into two functions, one that is
> only called from inside the NAPI context and one that is called for all
> other contexts?  It would mean having to double the number of pages
> being held per CPU, but I would think something like that would be doable.

Possibly, but this looks like code bloat for me.

On my hosts, this hard irq masking is pure noise.

What CPU are you using Alexander ?

Same could be done with some kmem_cache_alloc() : SLAB uses hard irq
masking while some caches are never used from hard irq context.



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