From: Andrew Cooper <andrew.cooper3@citrix.com>
To: George Dunlap <George.Dunlap@eu.citrix.com>
Cc: Xen-devel <xen-devel@lists.xen.org>
Subject: Re: [PATCH 0/2] Improvements with noreturn
Date: Mon, 25 Nov 2013 14:02:09 +0000 [thread overview]
Message-ID: <52935861.40704@citrix.com> (raw)
In-Reply-To: <CAFLBxZYw2gyXjiy8wobFGokOmiOyiatPHQXSqh==y53ka8YV+w@mail.gmail.com>
On 25/11/13 11:47, George Dunlap wrote:
> On Mon, Nov 25, 2013 at 10:25 AM, Andrew Cooper
> <andrew.cooper3@citrix.com> wrote:
>> Make better use of noreturn. It allows optimising compilers to produce more
>> efficient code.
>>
>> George:
>> I request that this is included for 4.4 - It is no functional change, but
>> quite a nice improvement in terms of code size.
> No functional change *if compilers are correct*. If they're not, for
> any reason, it will be very difficult to actually catch between now
> and the release.
>
> I'm not inclined to think that a reduction of 6k is a big enough
> improvement to take the risk at this point.
>
> -George
Patch 1 is literally just textual replacement, cleaning up its current
uses in the codebase.
Patch 2 applies its use to more functions in the codebase.
While I agree that it is "No functional change if compilers are
correct", this kind of paranoia could be applied to any and every patch
we consider taking. Anyway, Linux uses it far more than we do at the
moment.
As for difficulty to catch regressions, I would disagree. Failures to
reboot correctly will not pass the oss test, and the other alternative
is failures to crash correctly.
~Andrew
next prev parent reply other threads:[~2013-11-25 14:02 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-25 10:25 [PATCH 0/2] Improvements with noreturn Andrew Cooper
2013-11-25 10:25 ` [PATCH 1/2] xen/compiler: Replace opencoded __attribute__((noreturn)) Andrew Cooper
2013-11-25 10:31 ` Ian Campbell
2013-11-25 10:45 ` Tim Deegan
2013-11-25 10:57 ` Jan Beulich
2013-11-25 10:25 ` [PATCH 2/2] xen: Identify panic and reboot/halt functions as noreturn Andrew Cooper
2013-11-25 10:34 ` Ian Campbell
2013-11-25 10:37 ` Andrew Cooper
2013-11-25 10:45 ` Tim Deegan
2013-11-25 11:47 ` [PATCH 0/2] Improvements with noreturn George Dunlap
2013-11-25 14:02 ` Andrew Cooper [this message]
2013-11-25 14:46 ` George Dunlap
2013-11-25 14:50 ` Andrew Cooper
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