From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>,
Rusty Russell <rusty@rustcorp.com.au>,
qemu-devel@nongnu.org, Anthony Liguori <anthony@codemonkey.ws>,
David Gibson <david@gibson.dropbear.id.au>
Subject: Re: [Qemu-devel] [PATCH] Add a memory barrier to DMA functions
Date: Wed, 23 May 2012 07:24:01 +1000 [thread overview]
Message-ID: <1337721841.3038.15.camel@pasglop> (raw)
In-Reply-To: <20120522120358.GA3504@redhat.com>
On Tue, 2012-05-22 at 15:03 +0300, Michael S. Tsirkin wrote:
> I have a deja vu. Amos sent perf results when you argued about
> exactly the same issue in guest virtio. Delta was small but
> measureable. At the moment I have no free time or free hardware
> to redo the same work all over again. It's a well known fact that
> actual memory barrier is slow on x86 CPUs. You can't see
> it with network on your laptop? Write a microbenchmark.
Or just screw it, it's small enough, for emulated devices we can swallow
it, and move on with life, since virtio is unaffected, and we can always
fine tune e1000 if performance of that one is critical.
Ben.
next prev parent reply other threads:[~2012-05-22 21:24 UTC|newest]
Thread overview: 89+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-10 4:48 [Qemu-devel] [PATCH 00/13] IOMMU infrastructure Benjamin Herrenschmidt
2012-05-10 4:48 ` [Qemu-devel] [PATCH 01/13] Better support for dma_addr_t variables Benjamin Herrenschmidt
2012-05-10 4:48 ` [Qemu-devel] [PATCH 02/13] Implement cpu_physical_memory_zero() Benjamin Herrenschmidt
2012-05-15 0:42 ` Anthony Liguori
2012-05-15 1:23 ` David Gibson
2012-05-15 2:03 ` Anthony Liguori
2012-05-10 4:48 ` [Qemu-devel] [PATCH 03/13] iommu: Add universal DMA helper functions Benjamin Herrenschmidt
2012-05-10 4:48 ` [Qemu-devel] [PATCH 04/13] usb-ohci: Use " Benjamin Herrenschmidt
2012-05-10 4:48 ` [Qemu-devel] [PATCH 05/13] iommu: Make sglists and dma_bdrv helpers use new universal DMA helpers Benjamin Herrenschmidt
2012-05-10 4:49 ` [Qemu-devel] [PATCH 06/13] ide/ahci: Use universal DMA helper functions Benjamin Herrenschmidt
2012-05-21 1:51 ` [Qemu-devel] [PATCH 06/13 - UPDATED] " Benjamin Herrenschmidt
2012-05-10 4:49 ` [Qemu-devel] [PATCH 07/13] usb: Convert usb_packet_{map, unmap} to universal DMA helpers Benjamin Herrenschmidt
2012-05-10 4:49 ` [Qemu-devel] [PATCH 08/13] iommu: Introduce IOMMU emulation infrastructure Benjamin Herrenschmidt
2012-05-15 0:49 ` Anthony Liguori
2012-05-15 1:42 ` David Gibson
2012-05-15 2:03 ` Anthony Liguori
2012-05-15 2:32 ` Benjamin Herrenschmidt
2012-05-15 2:50 ` Anthony Liguori
2012-05-15 3:02 ` Benjamin Herrenschmidt
2012-05-15 14:02 ` Anthony Liguori
2012-05-15 21:55 ` Benjamin Herrenschmidt
2012-05-15 22:02 ` Anthony Liguori
2012-05-15 23:08 ` Benjamin Herrenschmidt
2012-05-15 23:58 ` Anthony Liguori
2012-05-16 0:41 ` Benjamin Herrenschmidt
2012-05-16 0:54 ` Anthony Liguori
2012-05-16 1:20 ` Benjamin Herrenschmidt
2012-05-16 19:36 ` Anthony Liguori
2012-05-10 4:49 ` [Qemu-devel] [PATCH 09/13] iommu: Add facility to cancel in-use dma memory maps Benjamin Herrenschmidt
2012-05-10 4:49 ` [Qemu-devel] [PATCH 10/13] pseries: Convert sPAPR TCEs to use generic IOMMU infrastructure Benjamin Herrenschmidt
2012-05-10 4:49 ` [Qemu-devel] [PATCH 11/13] iommu: Allow PCI to use " Benjamin Herrenschmidt
2012-05-10 4:49 ` [Qemu-devel] [PATCH 12/13] pseries: Implement IOMMU and DMA for PAPR PCI devices Benjamin Herrenschmidt
2012-05-10 4:49 ` [Qemu-devel] [PATCH 13/13] iommu: Add a memory barrier to DMA RW function Benjamin Herrenschmidt
2012-05-15 0:52 ` Anthony Liguori
2012-05-15 1:11 ` Benjamin Herrenschmidt
2012-05-15 1:44 ` David Gibson
2012-05-16 4:35 ` Benjamin Herrenschmidt
2012-05-16 5:51 ` David Gibson
2012-05-16 19:39 ` Anthony Liguori
2012-05-16 21:10 ` Benjamin Herrenschmidt
2012-05-16 21:12 ` Benjamin Herrenschmidt
2012-05-17 0:07 ` Benjamin Herrenschmidt
2012-05-17 0:24 ` Benjamin Herrenschmidt
2012-05-17 0:52 ` [Qemu-devel] [RFC/PATCH] Add a memory barrier to guest memory access functions Benjamin Herrenschmidt
2012-05-17 2:28 ` Anthony Liguori
2012-05-17 2:44 ` Benjamin Herrenschmidt
2012-05-17 22:09 ` Anthony Liguori
2012-05-18 1:04 ` David Gibson
2012-05-18 1:16 ` Benjamin Herrenschmidt
2012-05-17 3:35 ` David Gibson
2012-05-18 6:53 ` [Qemu-devel] [PATCH 13/13] iommu: Add a memory barrier to DMA RW function Paolo Bonzini
2012-05-18 8:18 ` Benjamin Herrenschmidt
2012-05-18 8:57 ` Paolo Bonzini
2012-05-18 22:26 ` Benjamin Herrenschmidt
2012-05-19 7:24 ` Paolo Bonzini
2012-05-20 21:36 ` Benjamin Herrenschmidt
2012-05-21 1:56 ` [Qemu-devel] [PATCH] Add a memory barrier to guest memory access functions Benjamin Herrenschmidt
2012-05-21 8:11 ` Paolo Bonzini
2012-05-21 8:31 ` Michael S. Tsirkin
2012-05-21 8:58 ` Benjamin Herrenschmidt
2012-05-21 9:07 ` Benjamin Herrenschmidt
2012-05-21 9:16 ` Benjamin Herrenschmidt
2012-05-21 9:34 ` Michael S. Tsirkin
2012-05-21 9:53 ` Benjamin Herrenschmidt
2012-05-21 10:31 ` Michael S. Tsirkin
2012-05-21 11:45 ` Benjamin Herrenschmidt
2012-05-21 12:18 ` Michael S. Tsirkin
2012-05-21 15:16 ` Paolo Bonzini
2012-05-21 21:58 ` [Qemu-devel] [PATCH] Add a memory barrier to guest memory access function Benjamin Herrenschmidt
2012-05-21 22:22 ` Michael S. Tsirkin
2012-05-21 22:56 ` Benjamin Herrenschmidt
2012-05-22 5:11 ` Michael S. Tsirkin
2012-05-22 0:00 ` Benjamin Herrenschmidt
2012-05-22 4:19 ` Rusty Russell
2012-05-21 22:18 ` [Qemu-devel] [PATCH] Add a memory barrier to guest memory access functions Anthony Liguori
2012-05-21 22:26 ` Benjamin Herrenschmidt
2012-05-21 22:31 ` Anthony Liguori
2012-05-21 22:44 ` Michael S. Tsirkin
2012-05-21 23:02 ` Benjamin Herrenschmidt
2012-05-22 4:34 ` [Qemu-devel] [PATCH] Add a memory barrier to DMA functions Benjamin Herrenschmidt
2012-05-22 4:51 ` Benjamin Herrenschmidt
2012-05-22 7:17 ` Benjamin Herrenschmidt
2012-05-22 11:14 ` Michael S. Tsirkin
2012-05-22 11:41 ` Benjamin Herrenschmidt
2012-05-22 12:03 ` Michael S. Tsirkin
2012-05-22 21:24 ` Benjamin Herrenschmidt [this message]
2012-05-22 21:40 ` Anthony Liguori
2012-05-21 22:37 ` [Qemu-devel] [PATCH] Add a memory barrier to guest memory access functions Michael S. Tsirkin
2012-05-15 0:52 ` [Qemu-devel] [PATCH 00/13] IOMMU infrastructure Anthony Liguori
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