From: "LIZHAOXIN1 [李照鑫]" <LIZHAOXIN1@kingsoft.com>
To: "Dr. David Alan Gilbert" <dgilbert@redhat.com>,
"Daniel P. Berrangé" <berrange@redhat.com>
Cc: "sunhao2 [孙昊]" <sunhao2@kingsoft.com>,
"YANGFENG1 [杨峰]" <YANGFENG1@kingsoft.com>,
"quintela@redhat.com" <quintela@redhat.com>,
"DENGLINWEN [邓林文]" <DENGLINWEN@kingsoft.com>,
"qemu-devel@nongnu.org" <qemu-devel@nongnu.org>,
"LIZHAOXIN1 [李照鑫]" <LIZHAOXIN1@kingsoft.com>
Subject: 回复: [PATCH] migration/rdma: Use huge page register VM memory
Date: Thu, 10 Jun 2021 15:35:40 +0000 [thread overview]
Message-ID: <0916045c71684f57b4fbe35ea876e991@kingsoft.com> (raw)
In-Reply-To: <YL40jJgKFQBnq3Us@work-vm>
Yes, When I configured two NUMAs for the VM, the name of the memory
is 'ram-node*', and other architectures had different names.
As you suggested, I use qemu_ram_pagesize() and qemu_real_host_page_size
to determine which Ramblocks use huge page.
I will send the patch second version later.
when there's a mix of different huge page sizes, there is no difference in their
behavior, register or pin are just to prevent the memory from being swapped out.
Huge page itself will not be swapped out，so huge page no need deregister or unpin.
The libvirt xml of my VM is
...
<memoryBacking>
<hugepages>
<page size='2048' unit='KiB' nodeset='0'/>
<page size='1048576' unit='KiB' nodeset='1'/>
</hugepages>
</memoryBacking>
...
<numa>
<cell id='0' cpus='0-7' memory='31457280' unit='KiB' memAccess='shared'/>
<cell id='1' cpus='8-15' memory='2097152' unit='KiB' memAccess='shared'/>
</numa>
...
After testing, the RDMA live migration is normal, and the downtime is significantly reduced.
-----邮件原件-----
发件人: Dr. David Alan Gilbert <dgilbert@redhat.com>
发送时间: 2021年6月7日 23:00
收件人: Daniel P. Berrangé <berrange@redhat.com>
抄送: LIZHAOXIN1 [李照鑫] <LIZHAOXIN1@kingsoft.com>; qemu-devel@nongnu.org; quintela@redhat.com; sunhao2 [孙昊] <sunhao2@kingsoft.com>; DENGLINWEN [邓林文] <DENGLINWEN@kingsoft.com>; YANGFENG1 [杨峰] <YANGFENG1@kingsoft.com>
主题: Re: [PATCH] migration/rdma: Use huge page register VM memory
* Daniel P. Berrangé (berrange@redhat.com) wrote:
> On Mon, Jun 07, 2021 at 01:57:02PM +0000, LIZHAOXIN1 [李照鑫] wrote:
> > When using libvirt for RDMA live migration, if the VM memory is too
> > large, it will take a lot of time to deregister the VM at the source
> > side, resulting in a long downtime (VM 64G, deregister vm time is about 400ms).
> >
> > Although the VM's memory uses 2M huge pages, the MLNX driver still
> > uses 4K pages for pin memory, as well as for unpin. So we use huge
> > pages to skip the process of pin memory and unpin memory to reduce downtime.
> >
> > The test environment:
> > kernel: linux-5.12
> > MLNX: ConnectX-4 LX
> > libvirt command:
> > virsh migrate --live --p2p --persistent --copy-storage-inc
> > --listen-address \
> > 0.0.0.0 --rdma-pin-all --migrateuri rdma://192.168.0.2 [VM]
> > qemu+tcp://192.168.0.2/system
> >
> > Signed-off-by: lizhaoxin <lizhaoxin1@kingsoft.com>
> >
> > diff --git a/migration/rdma.c b/migration/rdma.c index
> > 1cdb4561f3..9823449297 100644
> > --- a/migration/rdma.c
> > +++ b/migration/rdma.c
> > @@ -1123,13 +1123,26 @@ static int qemu_rdma_reg_whole_ram_blocks(RDMAContext *rdma)
> > RDMALocalBlocks *local = &rdma->local_ram_blocks;
> >
> > for (i = 0; i < local->nb_blocks; i++) {
> > - local->block[i].mr =
> > - ibv_reg_mr(rdma->pd,
> > - local->block[i].local_host_addr,
> > - local->block[i].length,
> > - IBV_ACCESS_LOCAL_WRITE |
> > - IBV_ACCESS_REMOTE_WRITE
> > - );
> > + if (strcmp(local->block[i].block_name,"pc.ram") == 0) {
>
> 'pc.ram' is an x86 architecture specific name, so this will still
> leave a problem on other architectures I assume.
Yes, and also break even on PC when using NUMA.
I think the thing to do here is to call qemu_ram_pagesize on the RAMBlock;
if (qemu_ram_pagesize(RAMBlock....) != qemu_real_host_page_size)
it's a huge page
I guess it's probably best to do that in qemu_rdma_init_one_block or something?
I wonder how that all works when there's a mix of different huge page sizes?
Dave
> > + local->block[i].mr =
> > + ibv_reg_mr(rdma->pd,
> > + local->block[i].local_host_addr,
> > + local->block[i].length,
> > + IBV_ACCESS_LOCAL_WRITE |
> > + IBV_ACCESS_REMOTE_WRITE |
> > + IBV_ACCESS_ON_DEMAND |
> > + IBV_ACCESS_HUGETLB
> > + );
> > + } else {
> > + local->block[i].mr =
> > + ibv_reg_mr(rdma->pd,
> > + local->block[i].local_host_addr,
> > + local->block[i].length,
> > + IBV_ACCESS_LOCAL_WRITE |
> > + IBV_ACCESS_REMOTE_WRITE
> > + );
> > + }
> > +
> > if (!local->block[i].mr) {
> > perror("Failed to register local dest ram block!\n");
> > break;
>
> Regards,
> Daniel
> --
> |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :|
> |: https://libvirt.org -o- https://fstop138.berrange.com :|
> |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
next prev parent reply other threads:[~2021-06-10 15:38 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-06-07 13:57 [PATCH] migration/rdma: Use huge page register VM memory LIZHAOXIN1 [李照鑫]
2021-06-07 14:17 ` Daniel P. Berrangé
2021-06-07 15:00 ` Dr. David Alan Gilbert
2021-06-10 15:35 ` LIZHAOXIN1 [李照鑫] [this message]
2021-06-10 15:33 ` 回复: " LIZHAOXIN1 [李照鑫]
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=0916045c71684f57b4fbe35ea876e991@kingsoft.com \
--to=lizhaoxin1@kingsoft.com \
--cc=DENGLINWEN@kingsoft.com \
--cc=YANGFENG1@kingsoft.com \
--cc=berrange@redhat.com \
--cc=dgilbert@redhat.com \
--cc=qemu-devel@nongnu.org \
--cc=quintela@redhat.com \
--cc=sunhao2@kingsoft.com \
/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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).