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From: Sergio Lopez <slp@redhat.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] Flatview rendering scalability issue
Date: Mon, 11 Mar 2019 14:48:48 +0100	[thread overview]
Message-ID: <87zhq1ed33.fsf@redhat.com> (raw)
In-Reply-To: <3fd4f68a-9ce4-7e54-a763-ccdcf844890e@redhat.com>


Paolo Bonzini writes:

> On 11/03/19 10:26, Sergio Lopez wrote:
>> I guess this is a consequence of having to reset/rebuild the Flatview
>> when altering the PCI BAR regions.
>> 
>> Is this a known issue we're already working on?
>
> What version of QEMU is this?

This upstream as of 6cb4f6db4f4367f (Mar 07 2019).

> The initialization is O(n^2) because the guest initializes one device at
> a time, so you rebuild the FlatView first with 0 devices, then 1, then
> 2, etc.  This is very hard to fix, if at all possible.
>
> However, each FlatView creation should be O(n) where n is the number of
> devices currently configured.  Please check with "info mtree -f" that
> you only have a fixed number of FlatViews.  Old versions had one per device.

I'm seeing 9 FVs with 1 PCI, and 119 with 100 PCIs.

Thanks,
Sergio.

  reply	other threads:[~2019-03-11 13:54 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-11  9:26 [Qemu-devel] Flatview rendering scalability issue Sergio Lopez
2019-03-11 10:19 ` Paolo Bonzini
2019-03-11 13:48   ` Sergio Lopez [this message]
2019-03-11 14:07     ` Paolo Bonzini
2019-03-11 14:35       ` Sergio Lopez
2019-03-12  3:23       ` Peter Xu

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