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Re: [Qemu-devel] IVSHMEM device performance
From: |
Markus Armbruster |
Subject: |
Re: [Qemu-devel] IVSHMEM device performance |
Date: |
Mon, 11 Apr 2016 10:56:54 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.5 (gnu/linux) |
Cc: qemu-devel
Eli Britstein <address@hidden> writes:
> Hi
>
> In a VM, I add a IVSHMEM device, on which the MBUFS mempool resides, and also
> rings I create (I run a DPDK application in the VM).
> I saw there is a performance penalty if I use such device, instead of
> hugepages (the VM's hugepages). My VM's memory is *NOT* backed with host's
> hugepages.
> The memory behind the IVSHMEM device is a host hugepage (I use a patched
> version of QEMU, as provided by Intel).
> 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, but I am not sure.
> So, my direction was to change the kernel (in the VM) so it will consider
> this memory as a regular memory (and thus cached), instead of a PCI memory
> region.
> However, I am not sure my direction is correct, and even if so, I am not sure
> how/where to change the kernel (my starting point was mm/mmap.c, but I'm not
> sure it's the correct place to start).
>
> Any suggestion is welcomed.
> Thanks,
> Eli.
- Re: [Qemu-devel] IVSHMEM device performance,
Markus Armbruster <=