From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: "Jürgen Groß" <jgross@suse.com>,
xen-devel@lists.xenproject.org, x86@kernel.org,
linux-kernel@vger.kernel.org,
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"Ingo Molnar" <mingo@redhat.com>,
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"Boris Ostrovsky" <boris.ostrovsky@oracle.com>,
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"Ben Segall" <bsegall@google.com>, "Mel Gorman" <mgorman@suse.de>,
"Daniel Bristot de Oliveira" <bristot@redhat.com>
Subject: Re: [PATCH v2 00/12] x86: major paravirt cleanup
Date: Wed, 16 Dec 2020 10:56:05 -0600 [thread overview]
Message-ID: <20201216165605.4h5q7os5dutjgdqi@treble> (raw)
In-Reply-To: <20201216084059.GL3040@hirez.programming.kicks-ass.net>
On Wed, Dec 16, 2020 at 09:40:59AM +0100, Peter Zijlstra wrote:
> > So much algorithm.
>
> :-)
>
> It's not really hard, but it has a few pesky details (as always).
It really hurt my brain to look at it.
> > Could we make it easier by caching the shared
> > per-alt-group CFI state somewhere along the way?
>
> Yes, but when I tried it grew the code required. Runtime costs would be
> less, but I figured that since alternatives are typically few and small,
> that wasn't a real consideration.
Aren't alternatives going to be everywhere now with paravirt using them?
> That is, it would basically cache the results of find_alt_unwind(), but
> you still need find_alt_unwind() to generate that data, and so you gain
> the code for filling and using the extra data structure.
>
> Yes, computing it 3 times is naf, but meh.
Haha, I loved this sentence.
> > Thoughts? This is all theoretical of course, I could try to do a patch
> > tomorrow.
>
> No real objection, I just didn't do it because 1) it works, and 2) even
> moar lines.
I'm kind of surprised it would need moar lines. Let me play around with
it and maybe I'll come around ;-)
--
Josh
next prev parent reply other threads:[~2020-12-16 16:58 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-20 11:46 [PATCH v2 00/12] x86: major paravirt cleanup Juergen Gross
2020-11-20 11:46 ` [PATCH v2 06/12] x86/paravirt: switch time pvops functions to use static_call() Juergen Gross
2020-11-20 12:01 ` Peter Zijlstra
2020-11-20 12:07 ` Jürgen Groß
2020-11-20 12:53 ` [PATCH v2 00/12] x86: major paravirt cleanup Peter Zijlstra
2020-11-23 13:43 ` Peter Zijlstra
2020-12-15 11:42 ` Jürgen Groß
2020-12-15 14:18 ` Peter Zijlstra
2020-12-15 14:54 ` Peter Zijlstra
2020-12-15 15:07 ` Jürgen Groß
2020-12-16 0:38 ` Josh Poimboeuf
2020-12-16 8:40 ` Peter Zijlstra
2020-12-16 16:56 ` Josh Poimboeuf [this message]
2020-12-16 17:58 ` Peter Zijlstra
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