From: Markus Armbruster <armbru@redhat.com>
To: Eli Britstein <eli.britstein@toganetworks.com>
Cc: "kvm\@vger.kernel.org" <kvm@vger.kernel.org>, qemu-devel@nongnu.org
Subject: Re: IVSHMEM device performance
Date: Mon, 11 Apr 2016 10:56:54 +0200 [thread overview]
Message-ID: <87fuuso755.fsf@dusky.pond.sub.org> (raw)
In-Reply-To: <VI1PR02MB17275FD1274A0D7C24956E8283940@VI1PR02MB1727.eurprd02.prod.outlook.com> (Eli Britstein's message of "Mon, 11 Apr 2016 06:21:24 +0000")
Cc: qemu-devel
Eli Britstein <eli.britstein@toganetworks.com> 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.
WARNING: multiple messages have this Message-ID (diff)
From: Markus Armbruster <armbru@redhat.com>
To: Eli Britstein <eli.britstein@toganetworks.com>
Cc: "kvm@vger.kernel.org" <kvm@vger.kernel.org>, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] IVSHMEM device performance
Date: Mon, 11 Apr 2016 10:56:54 +0200 [thread overview]
Message-ID: <87fuuso755.fsf@dusky.pond.sub.org> (raw)
In-Reply-To: <VI1PR02MB17275FD1274A0D7C24956E8283940@VI1PR02MB1727.eurprd02.prod.outlook.com> (Eli Britstein's message of "Mon, 11 Apr 2016 06:21:24 +0000")
Cc: qemu-devel
Eli Britstein <eli.britstein@toganetworks.com> 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.
next prev parent reply other threads:[~2016-04-11 8:56 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-11 6:21 IVSHMEM device performance Eli Britstein
2016-04-11 8:56 ` Markus Armbruster [this message]
2016-04-11 8:56 ` [Qemu-devel] " Markus Armbruster
2016-04-11 12:27 ` Michael S. Tsirkin
2016-04-11 12:27 ` [Qemu-devel] " Michael S. Tsirkin
2016-04-11 13:18 ` Eli Britstein
2016-04-11 13:18 ` [Qemu-devel] " Eli Britstein
2016-04-11 16:07 ` Eric Blake
2016-04-14 2:16 ` Wang, Wei W
2016-04-14 12:45 ` Paolo Bonzini
2016-04-17 7:18 ` Eli Britstein
2016-04-17 12:03 ` Paolo Bonzini
2016-04-17 15:57 ` Eli Britstein
2016-05-05 8:57 ` Eli Britstein
2016-05-06 0:50 ` Wang, Wei W
2016-05-08 6:12 ` Eli Britstein
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=87fuuso755.fsf@dusky.pond.sub.org \
--to=armbru@redhat.com \
--cc=eli.britstein@toganetworks.com \
--cc=kvm@vger.kernel.org \
--cc=qemu-devel@nongnu.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.