Messages in this thread | | | Subject | Re: [PATCH 1/1] Defer skb allocation for both mergeable buffers and big packets in virtio_net | From | Shirley Ma <> | Date | Mon, 23 Nov 2009 08:18:08 -0800 |
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On Mon, 2009-11-23 at 11:43 +0200, Michael S. Tsirkin wrote:
> should be !npage->private > and nesting is too deep here: > this is cleaner in a give_a_page subroutine > as it was.
This will be addressed with Rusty's comment.
> > + /* use private to chain big packets */ > > packets? or pages?
Will change it to chain pages for big packets
> > + p->private = (unsigned long)0; > > the comment is not really helpful: > you say you use private to chain but 0 does not > chain anything. You also do not need the cast to long?
Ok.
> > + if (len > (PAGE_SIZE - f->page_offset)) > > brackets around math are not needed.
OK.
> typo > > > + * header and data */ Got it.
> please think of a way to get rid of magic constants like 6 and 2 > here and elsewhere.
Will do.
> replace MAX_SKB_FRAGS + 2 with something symbolic? We have it in 2 palces now. > And comment.
Ok, I can change it.
> terrible goto based loop > move stuff into subfunction, it will be much > more manageable, and convert this to a simple > for loop.
Will change it to different functions based on Rusty's comment.
> and here it is MAX_SKB_FRAGS + 1
I think I should use MAX_SKB_FRAGS + 2 instead. Now I only use MAX_SKB_FRAGS + 1 but allocated + 2.
> > + page->private = (unsigned long)first_page; > > + first_page = page; > > + if (--i == 1) { > > this is pretty hairy ... has to be this way? > What you are trying to do here > is fill buffer with pages, in a loop, with first one > using a partial page, and then add it. > Is that it? Yes.
> So please code this in a straight forward manner. > it should be as simple as:
> offset = XXX > for (i = 0; i < MAX_SKB_FRAGS + 2; ++i) { > > sg_set_buf(sg + i, p + offset, PAGE_SIZE - offset); > offset = 0; > > } Ok, looks more neat.
> space around + > sg + 1 here is same as &sg[i] in fact?
Ok.
> callback -> destructor?
Ok.
I will integrate these comments with Rusty's and resubmit the patch set.
Thanks Shirley
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