Re: [Lhms-devel] [PATCH 0/7] Fragmentation Avoidance V19

[Nick Piggin]

KAMEZAWA Hiroyuki wrote:
> Martin J. Bligh wrote:

> please check kmalloc(32k,64k)
>
> For example, loopback device's default MTU=16436 means order=3 and
> maybe there are other high MTU device.
>
> I suspect skb_makewritable()/skb_copy()/skb_linearize() function can be
> sufferd from fragmentation when MTU is big. They allocs large skb by
> gathering fragmented skbs.When these skb_* funcs failed, the packet
> is silently discarded by netfilter. If fragmentation is heavy, packets
> (especialy TCP) uses large MTU never reachs its end, even if loopback.
>
> Honestly, I'm not familiar with network code, could anyone comment this ?

I'd be interested to know, actually. I was hoping loopback should always
use order-0 allocations, because the loopback driver is SG, FRAGLIST,
and HIGHDMA capable. However I'm likewise not familiar with network code.

--
SUSE Labs, Novell Inc.

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