Mailing List Archive

# HG changeset patch
# User kaf24@firebug.cl.cam.ac.uk
# Node ID d4ab8e46136ccb64a75dbdb6e84126d6a9552ca4
# Parent df68a9433492b024963334b124586f56885266fd
Blkif request notifications use generic ring req_event holdoff
mechanism rather than custom mechanism.

Signed-off-by: Keir Fraser <keir@xensource.com>

diff -r df68a9433492 -r d4ab8e46136c linux-2.6-xen-sparse/drivers/xen/blkback/blkback.c
--- a/linux-2.6-xen-sparse/drivers/xen/blkback/blkback.c Fri Dec 2 12:16:13 2005
+++ b/linux-2.6-xen-sparse/drivers/xen/blkback/blkback.c Fri Dec 2 12:27:39 2005
@@ -498,10 +498,14 @@
* notifications if requests are already in flight (lower overheads
* and promotes batching).
*/
- if (!__on_blkdev_list(blkif) &&
- RING_HAS_UNCONSUMED_REQUESTS(blk_ring)) {
- add_to_blkdev_list_tail(blkif);
- maybe_trigger_blkio_schedule();
+ mb();
+ if (!__on_blkdev_list(blkif)) {
+ int more_to_do;
+ RING_FINAL_CHECK_FOR_REQUESTS(blk_ring, more_to_do);
+ if (more_to_do) {
+ add_to_blkdev_list_tail(blkif);
+ maybe_trigger_blkio_schedule();
+ }
}

if (notify)
diff -r df68a9433492 -r d4ab8e46136c linux-2.6-xen-sparse/drivers/xen/blkfront/blkfront.c
--- a/linux-2.6-xen-sparse/drivers/xen/blkfront/blkfront.c Fri Dec 2 12:16:13 2005
+++ b/linux-2.6-xen-sparse/drivers/xen/blkfront/blkfront.c Fri Dec 2 12:27:39 2005
@@ -395,16 +395,11 @@

static inline void flush_requests(struct blkfront_info *info)
{
- RING_IDX old_prod = info->ring.sring->req_prod;
-
- RING_PUSH_REQUESTS(&info->ring);
-
- /*
- * Send new requests /then/ check if any old requests are still in
- * flight. If so then there is no need to send a notification.
- */
- mb();
- if (info->ring.sring->rsp_prod == old_prod)
+ int notify;
+
+ RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&info->ring, notify);
+
+ if (notify)
notify_remote_via_irq(info->irq);
}

diff -r df68a9433492 -r d4ab8e46136c xen/include/public/io/blkif.h
--- a/xen/include/public/io/blkif.h Fri Dec 2 12:16:13 2005
+++ b/xen/include/public/io/blkif.h Fri Dec 2 12:27:39 2005
@@ -12,11 +12,10 @@
#include "ring.h"

/*
- * Front->back notifications: When enqueuing a new request, there is no
- * need to send a notification if there are old requests still in flight
- * (that is, old_req_prod != sring->rsp_prod). The backend guarantees to check
- * for new requests after queuing the response for the last in-flight request.
- * (NB. The generic req_event mechanism is not used for blk requests.)
+ * Front->back notifications: When enqueuing a new request, sending a
+ * notification can be made conditional on req_event (i.e., the generic
+ * hold-off mechanism provided by the ring macros). Backends must set
+ * req_event appropriately (e.g., using RING_FINAL_CHECK_FOR_REQUESTS()).
*
* Back->front notifications: When enqueuing a new response, sending a
* notification can be made conditional on rsp_event (i.e., the generic

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