Attachment 10800 Details for Bug 11124 – Patch for 4.2

[patch] Patch for 4.2

0001-ctdb-io-Do-not-use-sys_write-to-write-to-client-sock.patch (text/plain), 2.40 KB, created by Amitay Isaacs on 2015-02-27 04:21:03 UTC

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Creator: Amitay Isaacs

Created: 2015-02-27 04:21:03 UTC

Size: 2.40 KB

patch

obsolete

>From cb8e34b9c4c37dd76185f94a38bc8fb7c5972760 Mon Sep 17 00:00:00 2001
>From: Amitay Isaacs <amitay@gmail.com>
>Date: Mon, 23 Feb 2015 12:38:11 +1100
>Subject: [PATCH] ctdb-io: Do not use sys_write to write to client sockets
>
>When sending messages to clients, ctdb checks for EAGAIN error code and
>schedules next write in the subsequent event loop.  Using sys_write in
>these places causes ctdb to loop hard till a client is able to read from
>the socket.  With real time scheduling, ctdb daemon spins consuming 100%
>of CPU trying to write to the client sockets.  This can be quite harmful
>when running under VMs or machines with single CPU.
>
>This regression was introduced when all read/write calls were replaced to
>use sys_read/sys_write wrappers (c1558adeaa980fb4bd6177d36250ec8262e9b9fe).
>
>The existing code backs off in case of EAGAIN failures and waits for an
>event loop to process the write again.  This should give ctdb clients
>a chance to get scheduled and to process the ctdb socket.
>
>Signed-off-by: Amitay Isaacs <amitay@gmail.com>
>Reviewed-by: Martin Schwenke <martin@meltin.net>
>
>Autobuild-User(master): Martin Schwenke <martins@samba.org>
>Autobuild-Date(master): Tue Feb 24 12:29:30 CET 2015 on sn-devel-104
>
>(cherry picked from commit 04a061e4d19d5bdbd8179fb0fab8b0875eec243e)
>---
> ctdb/common/ctdb_io.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
>diff --git a/ctdb/common/ctdb_io.c b/ctdb/common/ctdb_io.c
>index 467ec9a..53486f4 100644
>--- a/ctdb/common/ctdb_io.c
>+++ b/ctdb/common/ctdb_io.c
>@@ -232,9 +232,9 @@ static void queue_io_write(struct ctdb_queue *queue)
> 		struct ctdb_queue_pkt *pkt = queue->out_queue;
> 		ssize_t n;
> 		if (queue->ctdb->flags & CTDB_FLAG_TORTURE) {
>-			n = sys_write(queue->fd, pkt->data, 1);
>+			n = write(queue->fd, pkt->data, 1);
> 		} else {
>-			n = sys_write(queue->fd, pkt->data, pkt->length);
>+			n = write(queue->fd, pkt->data, pkt->length);
> 		}
> 
> 		if (n == -1 && errno != EAGAIN && errno != EWOULDBLOCK) {
>@@ -310,7 +310,7 @@ int ctdb_queue_send(struct ctdb_queue *queue, uint8_t *data, uint32_t length)
> 	   queue overhead. This relies on non-blocking sockets */
> 	if (queue->out_queue == NULL && queue->fd != -1 &&
> 	    !(queue->ctdb->flags & CTDB_FLAG_TORTURE)) {
>-		ssize_t n = sys_write(queue->fd, data, length2);
>+		ssize_t n = write(queue->fd, data, length2);
> 		if (n == -1 && errno != EAGAIN && errno != EWOULDBLOCK) {
> 			talloc_free(queue->fde);
> 			queue->fde = NULL;
>-- 
>1.9.3
>

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Attachments on bug 11124: 10800