Subject: Re: [PATCH] tcp: splice as many packets as possible at once

From: Willy Tarreau <[email-masked]>
Date: Fri, 16 Jan 2009 00:44:08 +0100

On Fri, Jan 16, 2009 at 12:42:55AM +0100, Willy Tarreau wrote:
> On Thu, Jan 15, 2009 at 03:34:49PM -0800, David Miller wrote:
> > From: Herbert Xu <[email-masked]>
> > Date: Fri, 16 Jan 2009 10:32:05 +1100
> > 
> > > On Thu, Jan 15, 2009 at 03:26:08PM -0800, David Miller wrote:
> > > > +static inline struct page *linear_to_page(struct page *page, unsigned int len,
> > > > +					  unsigned int offset)
> > > > +{
> > > > +	struct page *p = alloc_pages(GFP_KERNEL, 0);
> > > > +
> > > > +	if (!p)
> > > > +		return NULL;
> > > > +	memcpy(page_address(p) + offset, page_address(page) + offset, len);
> > > 
> > > This won't work very well if skb->head is longer than a page.
> > > 
> > > We'll need to divide it up into individual pages.
> > 
> > Oh yes the same bug I pointed out the other day.
> > 
> > But Willy can test this patch as-is,
> 
> Hey, nice work Dave. +3% performance from your previous patch
> (31.6 MB/s). It's going fine and stable here.

And BTW feel free to add my Tested-by if you want in case you merge
this fix.

Willy