netdev - [PATCH net-next] net: add scheduling point in recvmmsg/sendmmsg

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Message-ID: <1452271040.8255.226.camel@edumazet-glaptop2.roam.corp.google.com>
Date:	Fri, 08 Jan 2016 08:37:20 -0800
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	David Miller <davem@...emloft.net>
Cc:	netdev <netdev@...r.kernel.org>,
	Willem de Bruijn <willemb@...gle.com>
Subject: [PATCH net-next] net: add scheduling point in recvmmsg/sendmmsg

From: Eric Dumazet <edumazet@...gle.com>

Applications often have to reduce number of datagrams
they receive or send per system call to avoid starvation problems.

Really the kernel should take care of this by using cond_resched(),
so that applications can experiment bigger batch sizes.

Signed-off-by: Eric Dumazet <edumazet@...gle.com>
---
 net/socket.c |    2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/socket.c b/net/socket.c
index d730ef9dfbf0..91c2de6f5020 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -2041,6 +2041,7 @@ int __sys_sendmmsg(int fd, struct mmsghdr __user *mmsg, unsigned int vlen,
 		if (err)
 			break;
 		++datagrams;
+		cond_resched();
 	}
 
 	fput_light(sock->file, fput_needed);
@@ -2236,6 +2237,7 @@ int __sys_recvmmsg(int fd, struct mmsghdr __user *mmsg, unsigned int vlen,
 		/* Out of band data, return right away */
 		if (msg_sys.msg_flags & MSG_OOB)
 			break;
+		cond_resched();
 	}
 
 out_put: