RE: IVSHMEM device performance

Eli Britstein
2016-04-17T07:33:14Z

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Attached.
Also, if need to change ioremap to ioremap_cache, please advise where. I assume in mmap it is already too late.

> -----Original Message-----
> From: Paolo Bonzini [mailto:paolo.bonzini@gmail.com] On Behalf Of Paolo
> Bonzini
> Sent: Thursday, 14 April, 2016 3:45 PM
> To: Eli Britstein; kvm@vger.kernel.org
> Subject: Re: IVSHMEM device performance
>
>
>
> On 11/04/2016 08:21, Eli Britstein wrote:
> > I thought maybe the reason is that this memory is seen by the VM as a
> > mapped PCI memory region, so it is not cached,
>
> KVM actually overrides the type of the memory region and always makes it
> cached.
>
> Can you try sending the "lspci -vv" output?
>
> Paolo
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[-- Attachment #2: lspci_vv_ivshmem.txt --]
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00:04.0 RAM memory: Red Hat, Inc Inter-VM shared memory
Subsystem: Red Hat, Inc QEMU Virtual Machine
Physical Slot: 4
Control: I/O+ Mem+ BusMaster- SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR+ FastB2B- DisINTx-
Status: Cap- 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
Interrupt: pin A routed to IRQ 11
Region 0: Memory at febf2000 (32-bit, non-prefetchable) [size=256]
Region 2: Memory at e0000000 (64-bit, prefetchable) [size=256M]
Kernel modules: virtio_pci