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X-Received-From: 162.221.156.55 Subject: [Qemu-devel] [PATCH 3/3] xen-bus / xen-block: add support for event channel polling X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , Stefano Stabellini , Max Reitz , Paul Durrant , Stefan Hajnoczi , Anthony Perard Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" Content-Type: text/plain; charset="utf-8" This patch introduces a poll callback for event channel fd-s and uses this to invoke the channel callback function. To properly support polling, it is necessary for the event channel callback function to return a boolean saying whether it has done any useful work or not. Thus xen_block_dataplane_event() is modified to directly invoke xen_block_handle_requests() and the latter only returns true if it actually processes any requests. This also means that the call to qemu_bh_schedule() is moved into xen_block_complete_aio(), which is more intuitive since the only reason for doing a deferred poll of the shared ring should be because there were previously insufficient resources to fully complete a previous poll. Signed-off-by: Paul Durrant Reviewed-by: Anthony PERARD --- Cc: Stefan Hajnoczi Cc: Stefano Stabellini Cc: Anthony Perard Cc: Kevin Wolf Cc: Max Reitz --- hw/block/dataplane/xen-block.c | 17 +++++++++-------- hw/xen/xen-bus.c | 11 +++++++++-- include/hw/xen/xen-bus.h | 2 +- 3 files changed, 19 insertions(+), 11 deletions(-) diff --git a/hw/block/dataplane/xen-block.c b/hw/block/dataplane/xen-block.c index 1046f965c4..908bd27bbd 100644 --- a/hw/block/dataplane/xen-block.c +++ b/hw/block/dataplane/xen-block.c @@ -317,7 +317,9 @@ static void xen_block_complete_aio(void *opaque, int re= t) } xen_block_release_request(request); =20 - qemu_bh_schedule(dataplane->bh); + if (dataplane->more_work) { + qemu_bh_schedule(dataplane->bh); + } =20 done: aio_context_release(dataplane->ctx); @@ -514,12 +516,13 @@ static int xen_block_get_request(XenBlockDataPlane *d= ataplane, */ #define IO_PLUG_THRESHOLD 1 =20 -static void xen_block_handle_requests(XenBlockDataPlane *dataplane) +static bool xen_block_handle_requests(XenBlockDataPlane *dataplane) { RING_IDX rc, rp; XenBlockRequest *request; int inflight_atstart =3D dataplane->requests_inflight; int batched =3D 0; + bool done_something =3D false; =20 dataplane->more_work =3D 0; =20 @@ -551,6 +554,7 @@ static void xen_block_handle_requests(XenBlockDataPlane= *dataplane) } xen_block_get_request(dataplane, request, rc); dataplane->rings.common.req_cons =3D ++rc; + done_something =3D true; =20 /* parse them */ if (xen_block_parse_request(request) !=3D 0) { @@ -602,10 +606,7 @@ static void xen_block_handle_requests(XenBlockDataPlan= e *dataplane) blk_io_unplug(dataplane->blk); } =20 - if (dataplane->more_work && - dataplane->requests_inflight < dataplane->max_requests) { - qemu_bh_schedule(dataplane->bh); - } + return done_something; } =20 static void xen_block_dataplane_bh(void *opaque) @@ -617,11 +618,11 @@ static void xen_block_dataplane_bh(void *opaque) aio_context_release(dataplane->ctx); } =20 -static void xen_block_dataplane_event(void *opaque) +static bool xen_block_dataplane_event(void *opaque) { XenBlockDataPlane *dataplane =3D opaque; =20 - qemu_bh_schedule(dataplane->bh); + return xen_block_handle_requests(dataplane); } =20 XenBlockDataPlane *xen_block_dataplane_create(XenDevice *xendev, diff --git a/hw/xen/xen-bus.c b/hw/xen/xen-bus.c index 4f634d1291..c90fc62a8d 100644 --- a/hw/xen/xen-bus.c +++ b/hw/xen/xen-bus.c @@ -931,13 +931,20 @@ struct XenEventChannel { void *opaque; }; =20 +static bool xen_device_poll(void *opaque) +{ + XenEventChannel *channel =3D opaque; + + return channel->handler(channel->opaque); +} + static void xen_device_event(void *opaque) { XenEventChannel *channel =3D opaque; unsigned long port =3D xenevtchn_pending(channel->xeh); =20 if (port =3D=3D channel->local_port) { - channel->handler(channel->opaque); + xen_device_poll(channel); =20 xenevtchn_unmask(channel->xeh, port); } @@ -972,7 +979,7 @@ XenEventChannel *xen_device_bind_event_channel(XenDevic= e *xendev, =20 channel->ctx =3D ctx; aio_set_fd_handler(channel->ctx, xenevtchn_fd(channel->xeh), false, - xen_device_event, NULL, NULL, channel); + xen_device_event, NULL, xen_device_poll, channel); =20 QLIST_INSERT_HEAD(&xendev->event_channels, channel, list); =20 diff --git a/include/hw/xen/xen-bus.h b/include/hw/xen/xen-bus.h index 8183b98c7d..1c2d9dfdb8 100644 --- a/include/hw/xen/xen-bus.h +++ b/include/hw/xen/xen-bus.h @@ -119,7 +119,7 @@ void xen_device_copy_grant_refs(XenDevice *xendev, bool= to_domain, XenDeviceGrantCopySegment segs[], unsigned int nr_segs, Error **errp); =20 -typedef void (*XenEventHandler)(void *opaque); +typedef bool (*XenEventHandler)(void *opaque); =20 XenEventChannel *xen_device_bind_event_channel(XenDevice *xendev, AioContext *ctx, --=20 2.20.1.2.gb21ebb6