From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45967) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1W7lcX-0004YL-KW for qemu-devel@nongnu.org; Mon, 27 Jan 2014 07:49:03 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1W7lcP-0003pO-M4 for qemu-devel@nongnu.org; Mon, 27 Jan 2014 07:48:57 -0500 Received: from mx1.redhat.com ([209.132.183.28]:64607) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1W7lcP-0003pC-Dv for qemu-devel@nongnu.org; Mon, 27 Jan 2014 07:48:49 -0500 Received: from int-mx09.intmail.prod.int.phx2.redhat.com (int-mx09.intmail.prod.int.phx2.redhat.com [10.5.11.22]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id s0RCmmEI014555 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Mon, 27 Jan 2014 07:48:48 -0500 Date: Mon, 27 Jan 2014 13:48:44 +0100 From: Igor Mammedov Message-ID: <20140127134844.23dd840f@nial.usersys.redhat.com> In-Reply-To: <20140126103709.GA8844@redhat.com> References: <20140126103709.GA8844@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH] pcihp: reduce number of device check events List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Michael S. Tsirkin" Cc: qemu-devel@nongnu.org On Sun, 26 Jan 2014 12:37:09 +0200 "Michael S. Tsirkin" wrote: > PIIX created a made-up value for the UP register since it was read by > guest 32 times for each interrupt. > There's no reason to do this for the new PCIHP: register is only read > once for each interrupt, so clean up code by making read act as an > interrupt acknowledgement: the new UP register clear on read. > > In this way we cut down the number of bus rescans > by a factor of 32, and drop a bunch of code that's > now unused. > > Signed-off-by: Michael S. Tsirkin > --- > hw/acpi/pcihp.c | 21 +++++---------------- > include/hw/acpi/pcihp.h | 2 +- > 2 files changed, 6 insertions(+), 17 deletions(-) > > diff --git a/hw/acpi/pcihp.c b/hw/acpi/pcihp.c > index 3fa3d7c..4345f5d 100644 > --- a/hw/acpi/pcihp.c > +++ b/hw/acpi/pcihp.c > @@ -116,7 +116,6 @@ static void acpi_pcihp_eject_slot(AcpiPciHpState *s, unsigned bsel, unsigned slo > { > BusChild *kid, *next; > int slot = ffs(slots) - 1; > - bool slot_free = true; > PCIBus *bus = acpi_pcihp_find_hotplug_bus(s, bsel); > > if (!bus) { > @@ -125,21 +124,17 @@ static void acpi_pcihp_eject_slot(AcpiPciHpState *s, unsigned bsel, unsigned slo > > /* Mark request as complete */ > s->acpi_pcihp_pci_status[bsel].down &= ~(1U << slot); > + s->acpi_pcihp_pci_status[bsel].up &= ~(1U << slot); > > QTAILQ_FOREACH_SAFE(kid, &bus->qbus.children, sibling, next) { > DeviceState *qdev = kid->child; > PCIDevice *dev = PCI_DEVICE(qdev); > if (PCI_SLOT(dev->devfn) == slot) { > - if (acpi_pcihp_pc_no_hotplug(s, dev)) { > - slot_free = false; > - } else { > + if (!acpi_pcihp_pc_no_hotplug(s, dev)) { > object_unparent(OBJECT(qdev)); > } > } > } > - if (slot_free) { > - s->acpi_pcihp_pci_status[bsel].device_present &= ~(1U << slot); > - } > } > > static void acpi_pcihp_update_hotplug_bus(AcpiPciHpState *s, int bsel) > @@ -153,7 +148,6 @@ static void acpi_pcihp_update_hotplug_bus(AcpiPciHpState *s, int bsel) > } > > s->acpi_pcihp_pci_status[bsel].hotplug_enable = ~0; > - s->acpi_pcihp_pci_status[bsel].device_present = 0; > > if (!bus) { > return; > @@ -166,8 +160,6 @@ static void acpi_pcihp_update_hotplug_bus(AcpiPciHpState *s, int bsel) > if (acpi_pcihp_pc_no_hotplug(s, pdev)) { > s->acpi_pcihp_pci_status[bsel].hotplug_enable &= ~(1U << slot); > } > - > - s->acpi_pcihp_pci_status[bsel].device_present |= (1U << slot); > } > } > > @@ -187,7 +179,7 @@ void acpi_pcihp_reset(AcpiPciHpState *s) > > static void enable_device(AcpiPciHpState *s, unsigned bsel, int slot) > { > - s->acpi_pcihp_pci_status[bsel].device_present |= (1U << slot); > + s->acpi_pcihp_pci_status[bsel].up |= (1U << slot); > } > > static void disable_device(AcpiPciHpState *s, unsigned bsel, int slot) > @@ -208,7 +200,6 @@ int acpi_pcihp_device_hotplug(AcpiPciHpState *s, PCIDevice *dev, > * it is present on boot, no hotplug event is necessary. We do send an > * event when the device is disabled later. */ > if (state == PCI_COLDPLUG_ENABLED) { > - s->acpi_pcihp_pci_status[bsel].device_present |= (1U << slot); > return 0; > } > > @@ -233,10 +224,8 @@ static uint64_t pci_read(void *opaque, hwaddr addr, unsigned int size) > > switch (addr) { > case PCI_UP_BASE - PCI_HOTPLUG_ADDR: > - /* Manufacture an "up" value to cause a device check on any hotplug > - * slot with a device. Extra device checks are harmless. */ > - val = s->acpi_pcihp_pci_status[bsel].device_present & > - s->acpi_pcihp_pci_status[bsel].hotplug_enable; > + val = s->acpi_pcihp_pci_status[bsel].up; > + s->acpi_pcihp_pci_status[bsel].up = 0; > ACPI_PCIHP_DPRINTF("pci_up_read %" PRIu32 "\n", val); > break; > case PCI_DOWN_BASE - PCI_HOTPLUG_ADDR: > diff --git a/include/hw/acpi/pcihp.h b/include/hw/acpi/pcihp.h > index 6230e60..aa297c2 100644 > --- a/include/hw/acpi/pcihp.h > +++ b/include/hw/acpi/pcihp.h > @@ -32,7 +32,7 @@ > #include "hw/pci/pci.h" /* for PCIHotplugState */ > > typedef struct AcpiPciHpPciStatus { > - uint32_t up; /* deprecated, maintained for migration compatibility */ > + uint32_t up; > uint32_t down; > uint32_t hotplug_enable; > uint32_t device_present; After patch field AcpiPciHpPciStatus.device_present seem to be unused, should it be deleted here as well?