|To:||Anton Blanchard <anton@xxxxxxxxx>|
|Subject:||Re: [PATCH] TSO Reloaded|
|From:||"David S. Miller" <davem@xxxxxxxxxxxxx>|
|Date:||Thu, 5 May 2005 23:13:45 -0700|
|References:||<email@example.com> <20050506043653.GD8255@krispykreme> <20050506054516.GE8255@krispykreme>|
On Fri, 6 May 2005 15:45:16 +1000 Anton Blanchard <anton@xxxxxxxxx> wrote: > With a 9000 byte MTU I see page sized frags as expected. There are still > some pages broken in two which is interesting. I know what is causing the breaks, it's the "cache line align" crap in tcp_sendmsg(). Comment out this alignment code in net/ipv4/tcp.c and see how it goes: /* If page is cached, align * offset to L1 cache boundary */ off = (off + L1_CACHE_BYTES - 1) & ~(L1_CACHE_BYTES - 1); This alignment causes TSO coalescing to fail at these spots. You should not see this effect when sendfile() is used for the transfer.
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