Re: [Q] Default SLAB allocator

From: JoonSoo Kim
Date: Thu Oct 18 2012 - 20:03:50 EST

Hello, Eric.
Thank you very much for a kind comment about my question.
I have one more question related to network subsystem.
Please let me know what I misunderstand.

2012/10/14 Eric Dumazet <eric.dumazet@xxxxxxxxx>:
> In latest kernels, skb->head no longer use kmalloc()/kfree(), so SLAB vs
> SLUB is less a concern for network loads.
> In 3.7, (commit 69b08f62e17) we use fragments of order-3 pages to
> populate skb->head.

You mentioned that in latest kernel skb->head no longer use kmalloc()/kfree().
But, why result of David's "netperf RR" test on v3.6 is differentiated
by choosing the allocator?
As far as I know, __netdev_alloc_frag may be introduced in v3.5, so
I'm just confused.
Does this test use __netdev_alloc_skb with "__GFP_WAIT | GFP_DMA"?

Does normal workload for network use __netdev_alloc_skb with

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