From: Avi Kivity <avi@redhat.com>
To: zanghongyong@huawei.com
Cc: qemu-devel@nongnu.org, kvm@vger.kernel.org,
james.chenjiabo@huawei.com, wuchangyi@huawei.com,
xiaowei.yang@huawei.com, hanweidong@huawei.com,
wusongwei@huawei.com, louzhengwei@huawei.com, cam@cs.ualberta.ca
Subject: Re: [Qemu-devel] [PATCH] ivshmem: use PIO for BAR0(Doorbell) instead of MMIO to reduce notification time
Date: Thu, 17 Nov 2011 16:36:17 +0200 [thread overview]
Message-ID: <4EC51BE1.4050002@redhat.com> (raw)
In-Reply-To: <1321242993-28070-1-git-send-email-zanghongyong@huawei.com>
On 11/14/2011 05:56 AM, zanghongyong@huawei.com wrote:
> From: Hongyong Zang <zanghongyong@huawei.com>
>
> Ivshmem(nahanni) is a mechanism for sharing host memory with VMs running on the same host. Currently, guest notifies qemu by reading or writing ivshmem device's PCI MMIO BAR0(Doorbell).
>
> This patch, changes this PCI MMIO BAR0(Doorbell) to PIO. And we find guest accesses PIO BAR 30% faster than MMIO BAR.
>
> CharDriverState **eventfd_chr;
> CharDriverState *server_chr;
> - MemoryRegion ivshmem_mmio;
> + MemoryRegion ivshmem_pio;
>
> - pcibus_t mmio_addr;
> + pcibus_t pio_addr;
This is a backwards incompatible change. The way to accomplish this is
to add a new BAR which aliases the old one. The new BAR should not be
visible on guests created with -M pc-1.0 and below. Please also update
the spec so that driver authors can make use of the new feature.
--
error compiling committee.c: too many arguments to function
WARNING: multiple messages have this Message-ID (diff)
From: Avi Kivity <avi@redhat.com>
To: zanghongyong@huawei.com
Cc: wusongwei@huawei.com, kvm@vger.kernel.org, hanweidong@huawei.com,
qemu-devel@nongnu.org, wuchangyi@huawei.com,
xiaowei.yang@huawei.com, james.chenjiabo@huawei.com,
louzhengwei@huawei.com, cam@cs.ualberta.ca
Subject: Re: [Qemu-devel] [PATCH] ivshmem: use PIO for BAR0(Doorbell) instead of MMIO to reduce notification time
Date: Thu, 17 Nov 2011 16:36:17 +0200 [thread overview]
Message-ID: <4EC51BE1.4050002@redhat.com> (raw)
In-Reply-To: <1321242993-28070-1-git-send-email-zanghongyong@huawei.com>
On 11/14/2011 05:56 AM, zanghongyong@huawei.com wrote:
> From: Hongyong Zang <zanghongyong@huawei.com>
>
> Ivshmem(nahanni) is a mechanism for sharing host memory with VMs running on the same host. Currently, guest notifies qemu by reading or writing ivshmem device's PCI MMIO BAR0(Doorbell).
>
> This patch, changes this PCI MMIO BAR0(Doorbell) to PIO. And we find guest accesses PIO BAR 30% faster than MMIO BAR.
>
> CharDriverState **eventfd_chr;
> CharDriverState *server_chr;
> - MemoryRegion ivshmem_mmio;
> + MemoryRegion ivshmem_pio;
>
> - pcibus_t mmio_addr;
> + pcibus_t pio_addr;
This is a backwards incompatible change. The way to accomplish this is
to add a new BAR which aliases the old one. The new BAR should not be
visible on guests created with -M pc-1.0 and below. Please also update
the spec so that driver authors can make use of the new feature.
--
error compiling committee.c: too many arguments to function
next prev parent reply other threads:[~2011-11-17 14:36 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-14 3:56 [PATCH] ivshmem: use PIO for BAR0(Doorbell) instead of MMIO to reduce notification time zanghongyong
2011-11-14 3:56 ` [Qemu-devel] " zanghongyong
2011-11-15 18:43 ` Cam Macdonell
2011-11-15 18:43 ` Cam Macdonell
2011-11-17 12:42 ` Zang Hongyong
2011-11-17 12:42 ` Zang Hongyong
2011-11-17 14:36 ` Avi Kivity [this message]
2011-11-17 14:36 ` Avi Kivity
2011-11-17 14:48 ` Sasha Levin
2011-11-17 14:48 ` Sasha Levin
2011-11-17 15:10 ` Avi Kivity
2011-11-17 15:10 ` Avi Kivity
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