Re: [PATCH] tcp: splice as many packets as possible at once
From: Jarek Poplawski <hidden>
Date: 2009-01-16 06:51:36
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On Fri, Jan 16, 2009 at 12:44:08AM +0100, Willy Tarreau wrote:
On Fri, Jan 16, 2009 at 12:42:55AM +0100, Willy Tarreau wrote:quoted
On Thu, Jan 15, 2009 at 03:34:49PM -0800, David Miller wrote:quoted
From: Herbert Xu <herbert@gondor.apana.org.au> Date: Fri, 16 Jan 2009 10:32:05 +1100quoted
On Thu, Jan 15, 2009 at 03:26:08PM -0800, David Miller wrote:quoted
+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
Herbert, good catch! David, if it's not too late I think more credits are needed, especially for Willy. He did "a bit" more than testing. Alas, I can't see this problem with skb->head longer than page. There is even some comment on this in __splice_segment(), but I can miss something. I'm more concerned with memory usage if these skbs are not acked for some reason. Isn't there some DOS issue possible? Thanks everybody, Jarek P. ---------> Based on a review by Changli Gao [off-list ref]: http://lkml.org/lkml/2008/2/26/210 Foreseen-by: Changli Gao [off-list ref] Diagnosed-by: Willy Tarreau [off-list ref] Reported-by: Willy Tarreau <w@1wt.eu> Fixed-by: Jens Axboe [off-list ref] Signed-off-by: Jarek Poplawski <redacted>