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[Qemu-devel] [PATCH 12/12] ehci: Speed up the timer of raising int from
From: |
Hans de Goede |
Subject: |
[Qemu-devel] [PATCH 12/12] ehci: Speed up the timer of raising int from the async schedule |
Date: |
Mon, 8 Oct 2012 09:51:36 +0200 |
Often the guest will queue up new packets in response to a packet, in the
async schedule with its IOC flag set, completing. By speeding up the
frame-timer, we notice these new packets earlier. This increases the
speed (MB/s) of a Linux guest reading from a USB mass storage device by a
factor of 1.15 on top of the "Improve latency of interrupt delivery"
speed-ups, both with and without input pipelining enabled.
I've not tested the speed-up of this patch without the
"Improve latency of interrupt delivery" patch.
Signed-off-by: Hans de Goede <address@hidden>
---
hw/usb/hcd-ehci.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
diff --git a/hw/usb/hcd-ehci.c b/hw/usb/hcd-ehci.c
index fb3547d..5056618 100644
--- a/hw/usb/hcd-ehci.c
+++ b/hw/usb/hcd-ehci.c
@@ -443,6 +443,7 @@ struct EHCIState {
uint64_t last_run_ns;
uint32_t async_stepdown;
+ bool int_req_by_async;
};
#define SET_LAST_RUN_CLOCK(s) \
@@ -1546,6 +1547,9 @@ static void ehci_execute_complete(EHCIQueue *q)
if (q->qh.token & QTD_TOKEN_IOC) {
ehci_raise_irq(q->ehci, USBSTS_INT);
+ if (q->async) {
+ q->ehci->int_req_by_async = true;
+ }
}
}
@@ -2528,8 +2532,15 @@ static void ehci_frame_timer(void *opaque)
}
if (need_timer) {
- expire_time = t_now + (get_ticks_per_sec()
+ /* If we've raised int, we speed up the timer, so that we quickly
+ * notice any new packets queued up in response */
+ if (ehci->int_req_by_async && (ehci->usbsts & USBSTS_INT)) {
+ expire_time = t_now + get_ticks_per_sec() / (FRAME_TIMER_FREQ * 2);
+ ehci->int_req_by_async = false;
+ } else {
+ expire_time = t_now + (get_ticks_per_sec()
* (ehci->async_stepdown+1) / FRAME_TIMER_FREQ);
+ }
qemu_mod_timer(ehci->frame_timer, expire_time);
}
}
--
1.7.12.1
- [Qemu-devel] [PATCH 02/12] usb-redir: Add support for 32 bits bulk packet length, (continued)
- [Qemu-devel] [PATCH 02/12] usb-redir: Add support for 32 bits bulk packet length, Hans de Goede, 2012/10/08
- [Qemu-devel] [PATCH 01/12] usb-redir: When a packet contains data on a stall, ignore the stall, Hans de Goede, 2012/10/08
- [Qemu-devel] [PATCH 07/12] uhci: Add support for input queuing, Hans de Goede, 2012/10/08
- [Qemu-devel] [PATCH 08/12] ehci: Get rid of packet tbytes field, Hans de Goede, 2012/10/08
- [Qemu-devel] [PATCH 03/12] usb-host-linux: Only enabling pipeling for output endpoints, Hans de Goede, 2012/10/08
- [Qemu-devel] [PATCH 04/12] usb: Add support for input pipelining, Hans de Goede, 2012/10/08
- [Qemu-devel] [PATCH 06/12] uhci: Move checks to continue queuing to uhci_fill_queue(), Hans de Goede, 2012/10/08
- [Qemu-devel] [PATCH 05/12] uhci: Properly unmap packets on cancel / invalid pid, Hans de Goede, 2012/10/08
- [Qemu-devel] [PATCH 12/12] ehci: Speed up the timer of raising int from the async schedule,
Hans de Goede <=
- [Qemu-devel] [PATCH 09/12] ehci: Set int flag on a short input packet, Hans de Goede, 2012/10/08
- [Qemu-devel] [PATCH 10/12] ehci: Add support for input queuing, Hans de Goede, 2012/10/08
- [Qemu-devel] [PATCH 11/12] ehci: Improve latency of interrupt delivery and async schedule scanning, Hans de Goede, 2012/10/08