Re: [PATCH RFC V2 2/2] net: Optimize snmp stat aggregation by walking all the percpu data at once
From: Joe Perches
Date: Fri Aug 28 2015 - 17:26:29 EST
On Fri, 2015-08-28 at 14:14 -0700, Eric Dumazet wrote:
> On Fri, 2015-08-28 at 14:09 -0700, Joe Perches wrote:
> > On Fri, 2015-08-28 at 13:55 -0700, Eric Dumazet wrote:
> > > On Fri, 2015-08-28 at 13:53 -0700, Joe Perches wrote:
> > > > It's 288 bytes on stack, maybe a kzalloc would be clearer too.
> > >
> > > Could you read patch history and check why this has been rejected ?
> > I don't see a rejection, just that the initial
> > submission didn't check the allocation or add
> > an allocation buffer via kcalloc/kzalloc to the
> > inet6_fill_ifla6_attrs caller and change the
> > snmp6_fill_stats arguments.
> > It could also eliminate the put_unaligned calls.
> Not really. You do not properly read this code.
Always a possibility, but I don't think so.
> put_unaligned is happening on a space allocated from rtnetlink skb, not
> the temp space needed to perform the per cpu folding.
That's why I suggested changing the snmp_fill_stats arguments.
If the naturally aligned allocated u64 array is used and then
copied as a block to the rtnetlink skb, I believe there's no
alignment issue that would require put_unaligned.
Do I still miss something?
I read that.
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