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xen: introduce an event channel for buffered io event notifications

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Use the newly introduced HVM_PARAM_BUFIOREQ_EVTCHN to receive
notifications for buffered io events.
After the first notification is received leave the event channel masked
and setup a timer to process the rest of the batch.
Once we have completed processing the batch, unmask the event channel
and delete the timer.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
This commit is contained in:
Stefano Stabellini 2012-04-13 17:46:01 +00:00
parent 852a7cec90
commit fda1f76849
1 changed files with 39 additions and 6 deletions
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45
xen-all.c
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@ -59,6 +59,9 @@ static inline ioreq_t *xen_vcpu_ioreq(shared_iopage_t *shared_page, int vcpu)
}
# define FMT_ioreq_size "u"
#endif
#ifndef HVM_PARAM_BUFIOREQ_EVTCHN
#define HVM_PARAM_BUFIOREQ_EVTCHN 26
#endif
#define BUFFER_IO_MAX_DELAY 100
@ -77,6 +80,8 @@ typedef struct XenIOState {
QEMUTimer *buffered_io_timer;
/* the evtchn port for polling the notification, */
evtchn_port_t *ioreq_local_port;
/* evtchn local port for buffered io */
evtchn_port_t bufioreq_local_port;
/* the evtchn fd for polling */
XenEvtchn xce_handle;
/* which vcpu we are serving */
@ -629,6 +634,12 @@ static ioreq_t *cpu_get_ioreq(XenIOState *state)
evtchn_port_t port;
port = xc_evtchn_pending(state->xce_handle);
if (port == state->bufioreq_local_port) {
qemu_mod_timer(state->buffered_io_timer,
BUFFER_IO_MAX_DELAY + qemu_get_clock_ms(rt_clock));
return NULL;
}
if (port != -1) {
for (i = 0; i < smp_cpus; i++) {
if (state->ioreq_local_port[i] == port) {
@ -777,16 +788,18 @@ static void handle_ioreq(ioreq_t *req)
}
}
static void handle_buffered_iopage(XenIOState *state)
static int handle_buffered_iopage(XenIOState *state)
{
buf_ioreq_t *buf_req = NULL;
ioreq_t req;
int qw;
if (!state->buffered_io_page) {
return;
return 0;
}
memset(&req, 0x00, sizeof(req));
while (state->buffered_io_page->read_pointer != state->buffered_io_page->write_pointer) {
buf_req = &state->buffered_io_page->buf_ioreq[
state->buffered_io_page->read_pointer % IOREQ_BUFFER_SLOT_NUM];
@ -811,15 +824,21 @@ static void handle_buffered_iopage(XenIOState *state)
xen_mb();
state->buffered_io_page->read_pointer += qw ? 2 : 1;
}
return req.count;
}
static void handle_buffered_io(void *opaque)
{
XenIOState *state = opaque;
handle_buffered_iopage(state);
qemu_mod_timer(state->buffered_io_timer,
BUFFER_IO_MAX_DELAY + qemu_get_clock_ms(rt_clock));
if (handle_buffered_iopage(state)) {
qemu_mod_timer(state->buffered_io_timer,
BUFFER_IO_MAX_DELAY + qemu_get_clock_ms(rt_clock));
} else {
qemu_del_timer(state->buffered_io_timer);
xc_evtchn_unmask(state->xce_handle, state->bufioreq_local_port);
}
}
static void cpu_handle_ioreq(void *opaque)
@ -949,7 +968,6 @@ static void xen_main_loop_prepare(XenIOState *state)
state->buffered_io_timer = qemu_new_timer_ms(rt_clock, handle_buffered_io,
state);
qemu_mod_timer(state->buffered_io_timer, qemu_get_clock_ms(rt_clock));
if (evtchn_fd != -1) {
qemu_set_fd_handler(evtchn_fd, cpu_handle_ioreq, NULL, state);
@ -1050,6 +1068,7 @@ int xen_hvm_init(void)
{
int i, rc;
unsigned long ioreq_pfn;
unsigned long bufioreq_evtchn;
XenIOState *state;
state = g_malloc0(sizeof (XenIOState));
@ -1102,6 +1121,20 @@ int xen_hvm_init(void)
state->ioreq_local_port[i] = rc;
}
rc = xc_get_hvm_param(xen_xc, xen_domid, HVM_PARAM_BUFIOREQ_EVTCHN,
&bufioreq_evtchn);
if (rc < 0) {
fprintf(stderr, "failed to get HVM_PARAM_BUFIOREQ_EVTCHN\n");
return -1;
}
rc = xc_evtchn_bind_interdomain(state->xce_handle, xen_domid,
(uint32_t)bufioreq_evtchn);
if (rc == -1) {
fprintf(stderr, "bind interdomain ioctl error %d\n", errno);
return -1;
}
state->bufioreq_local_port = rc;
/* Init RAM management */
xen_map_cache_init(xen_phys_offset_to_gaddr, state);
xen_ram_init(ram_size);