Re: Major network performance regression in 3.7

[Eric Dumazet]

On Sun, 2013-01-06 at 10:51 -0800, Eric Dumazet wrote:
> > 
> > (sd->len is usually 4096, which is expected, but sd->total_len value is
> > huge in your case, so we always set the flag in fs/splice.c)
> 
> I am testing :
> 
>        if (sd->len < sd->total_len && pipe->nrbufs > 1)
>                 more |= MSG_SENDPAGE_NOTLAST;
> 

Yes, this should fix the problem :

If there is no following buffer in the pipe, we should not set NOTLAST.

diff --git a/fs/splice.c b/fs/splice.c
index 8890604..6909d89 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -696,8 +696,10 @@ static int pipe_to_sendpage(struct pipe_inode_info *pipe,
 		return -EINVAL;
 
 	more = (sd->flags & SPLICE_F_MORE) ? MSG_MORE : 0;
-	if (sd->len < sd->total_len)
+
+	if (sd->len < sd->total_len && pipe->nrbufs > 1)
 		more |= MSG_SENDPAGE_NOTLAST;
+
 	return file->f_op->sendpage(file, buf->page, buf->offset,
 				    sd->len, &pos, more);
 }


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