From b3d706dd43977c6be2eb5fe042d3cf9c21914963 Mon Sep 17 00:00:00 2001 From: Amit Shah Date: Fri, 4 Feb 2011 08:20:50 -0200 Subject: [RHEL6 qemu-kvm PATCH 19/27] virtio-console: Enable port throttling when chardev is slow to consume data RH-Author: Amit Shah Message-id: <4ec4fd6b5545a3b1775d2981c5f184b6edba7e55.1296806194.git.amit.shah@redhat.com> Patchwork-id: 17720 O-Subject: [RHEL6.1 qemu PATCH v5 19/19] virtio-console: Enable port throttling when chardev is slow to consume data Bugzilla: 588916 RH-Acked-by: Alon Levy RH-Acked-by: Juan Quintela RH-Acked-by: Jes Sorensen RH-Acked-by: Michael S. Tsirkin When a chardev indicates it can't accept more data, we tell the virtio-serial code to stop sending us any more data till we tell otherwise. This helps in guests continuing to run normally while the vq keeps getting full and eventually the guest stops queueing more data. As soon as the chardev indicates it can accept more data, start pushing! Signed-off-by: Amit Shah --- hw/virtio-console.c | 11 +++++++++++ 1 files changed, 11 insertions(+), 0 deletions(-) Signed-off-by: Eduardo Habkost --- hw/virtio-console.c | 11 +++++++++++ 1 files changed, 11 insertions(+), 0 deletions(-) diff --git a/hw/virtio-console.c b/hw/virtio-console.c index ccfa539..27ac475 100644 --- a/hw/virtio-console.c +++ b/hw/virtio-console.c @@ -18,6 +18,16 @@ typedef struct VirtConsole { CharDriverState *chr; } VirtConsole; +/* + * Callback function that's called from chardevs when backend becomes + * writable. + */ +static void chr_write_unblocked(void *opaque) +{ + VirtConsole *vcon = opaque; + + virtio_serial_throttle_port(&vcon->port, false); +} /* Callback function that's called when the guest sends us data */ static ssize_t flush_buf(VirtIOSerialPort *port, const uint8_t *buf, size_t len) @@ -61,6 +71,7 @@ static const QemuChrHandlers chr_handlers = { .fd_can_read = chr_can_read, .fd_read = chr_read, .fd_event = chr_event, + .fd_write_unblocked = chr_write_unblocked, }; static const QemuChrHandlers chr_handlers_no_flow_control = { -- 1.7.3.2