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authorEliezer Tamir <eliezer.tamir@linux.intel.com>2013-06-24 10:28:03 +0300
committerDavid S. Miller <davem@davemloft.net>2013-06-25 16:35:52 -0700
commit2d48d67fa8cd129ea85ea02d91b4a793286866f8 (patch)
treebe47e2406605760d949b08d29d988d46c4a20799 /net/socket.c
parente4f2379db6c6823c5d4a4c2c912df00c65de51d7 (diff)
downloadlwn-2d48d67fa8cd129ea85ea02d91b4a793286866f8.tar.gz
lwn-2d48d67fa8cd129ea85ea02d91b4a793286866f8.zip
net: poll/select low latency socket support
select/poll busy-poll support. Split sysctl value into two separate ones, one for read and one for poll. updated Documentation/sysctl/net.txt Add a new poll flag POLL_LL. When this flag is set, sock_poll will call sk_poll_ll if possible. sock_poll sets this flag in its return value to indicate to select/poll when a socket that can busy poll is found. When poll/select have nothing to report, call the low-level sock_poll again until we are out of time or we find something. Once the system call finds something, it stops setting POLL_LL, so it can return the result to the user ASAP. Signed-off-by: Eliezer Tamir <eliezer.tamir@linux.intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/socket.c')
-rw-r--r--net/socket.c14
1 files changed, 13 insertions, 1 deletions
diff --git a/net/socket.c b/net/socket.c
index 3eec3f76b49c..4da14cbd49b6 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -107,6 +107,7 @@
#include <net/ll_poll.h>
#ifdef CONFIG_NET_LL_RX_POLL
+unsigned int sysctl_net_ll_read __read_mostly;
unsigned int sysctl_net_ll_poll __read_mostly;
#endif
@@ -1147,13 +1148,24 @@ EXPORT_SYMBOL(sock_create_lite);
/* No kernel lock held - perfect */
static unsigned int sock_poll(struct file *file, poll_table *wait)
{
+ unsigned int ll_flag = 0;
struct socket *sock;
/*
* We can't return errors to poll, so it's either yes or no.
*/
sock = file->private_data;
- return sock->ops->poll(file, sock, wait);
+
+ if (sk_valid_ll(sock->sk)) {
+ /* this socket can poll_ll so tell the system call */
+ ll_flag = POLL_LL;
+
+ /* once, only if requested by syscall */
+ if (wait && (wait->_key & POLL_LL))
+ sk_poll_ll(sock->sk, 1);
+ }
+
+ return ll_flag | sock->ops->poll(file, sock, wait);
}
static int sock_mmap(struct file *file, struct vm_area_struct *vma)