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Re: [Qemu-devel] [PATCH v1 for-2-12 06/15] s390x/flic: factor out inject
From: |
Cornelia Huck |
Subject: |
Re: [Qemu-devel] [PATCH v1 for-2-12 06/15] s390x/flic: factor out injection of floating interrupts |
Date: |
Tue, 12 Dec 2017 16:28:39 +0100 |
On Tue, 12 Dec 2017 16:17:17 +0100
David Hildenbrand <address@hidden> wrote:
> On 12.12.2017 15:29, Cornelia Huck wrote:
> > On Tue, 12 Dec 2017 15:13:46 +0100
> > Christian Borntraeger <address@hidden> wrote:
> >
> >> On 12/12/2017 02:49 PM, Cornelia Huck wrote:
> >
> >>> One thing I noticed: You removed the caching of the flic (in the old
> >>> kvm inject routine), and you generally do more qom invocations (first,
> >>> to find the common flic; then, to translate to the qemu or kvm flic).
> >>> Not sure if this might be a problem (probably not).
> >>
> >> Is any of these calls on a potential fast path (e.g. guest without adapter
> >> interrupts)? If yes, then QOM is a no-go since it is really slow.
> >
> > At least the new airq interface was using QOM without caching before.
> >
> > It's basically about any interrupt; but otoh we are (for kvm) in
> > userspace already. Caching the flic and just keeping the casting to the
> > specialized flic might be ok (I'd guess that the lookup is the slowest
> > path.)
> >
>
> Please note that the lookup is already cached in s390_get_flic(); That
> should be sufficient, as it does the expensive lookup. One cache should
> be enough, no?
Ah, missed that. So the old code actually did double caching...
>
> The other conversions should be cheap (and already were in place in a
> couple of places before).
Yes, object_resolve_path() is probably the most expensive one.
Did anyone ever check if the (existing) conversions are actually
measurable?
[Qemu-devel] [PATCH v1 for-2-12 07/15] s390x/tcg: tolerate wrong wakeups due to floating interrupts, David Hildenbrand, 2017/12/11
[Qemu-devel] [PATCH v1 for-2-12 05/15] s390x/tcg: simplify machine check handling, David Hildenbrand, 2017/12/11
[Qemu-devel] [PATCH v1 for-2-12 06/15] s390x/flic: factor out injection of floating interrupts, David Hildenbrand, 2017/12/11
- Re: [Qemu-devel] [PATCH v1 for-2-12 06/15] s390x/flic: factor out injection of floating interrupts, Cornelia Huck, 2017/12/12
- Re: [Qemu-devel] [PATCH v1 for-2-12 06/15] s390x/flic: factor out injection of floating interrupts, Christian Borntraeger, 2017/12/12
- Re: [Qemu-devel] [PATCH v1 for-2-12 06/15] s390x/flic: factor out injection of floating interrupts, Cornelia Huck, 2017/12/12
- Re: [Qemu-devel] [PATCH v1 for-2-12 06/15] s390x/flic: factor out injection of floating interrupts, David Hildenbrand, 2017/12/12
- Re: [Qemu-devel] [PATCH v1 for-2-12 06/15] s390x/flic: factor out injection of floating interrupts,
Cornelia Huck <=
- Re: [Qemu-devel] [PATCH v1 for-2-12 06/15] s390x/flic: factor out injection of floating interrupts, Christian Borntraeger, 2017/12/13
- Re: [Qemu-devel] [PATCH v1 for-2-12 06/15] s390x/flic: factor out injection of floating interrupts, David Hildenbrand, 2017/12/13
- Re: [Qemu-devel] [PATCH v1 for-2-12 06/15] s390x/flic: factor out injection of floating interrupts, Christian Borntraeger, 2017/12/13
- Re: [Qemu-devel] [PATCH v1 for-2-12 06/15] s390x/flic: factor out injection of floating interrupts, Cornelia Huck, 2017/12/13
Re: [Qemu-devel] [PATCH v1 for-2-12 06/15] s390x/flic: factor out injection of floating interrupts, David Hildenbrand, 2017/12/12
[Qemu-devel] [PATCH v1 for-2-12 08/15] s390x/flic: make floating interrupts on TCG actually floating, David Hildenbrand, 2017/12/11
[Qemu-devel] [PATCH v1 for-2-12 09/15] s390x/tcg: implement TEST PENDING INTERRUPTION, David Hildenbrand, 2017/12/11