From: "Maciej W. Rozycki" <macro@linux-mips.org>
To: Paul Burton <paul.burton@mips.com>
Cc: Valentin Schneider <valentin.schneider@arm.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Ralf Baechle <ralf@linux-mips.org>,
James Hogan <jhogan@kernel.org>,
"linux-mips@vger.kernel.org" <linux-mips@vger.kernel.org>
Subject: Re: [PATCH 06/14] MIPS: entry: Remove unneeded need_resched() loop
Date: Fri, 10 May 2019 17:16:56 +0100 (BST) [thread overview]
Message-ID: <alpine.LFD.2.21.1905101706440.12665@eddie.linux-mips.org> (raw)
In-Reply-To: <20190314181306.k6vxmaomyqalhi65@pburton-laptop>
On Thu, 14 Mar 2019, Paul Burton wrote:
> > @@ -66,7 +65,7 @@ need_resched:
> > andi t0, 1
> > beqz t0, restore_all
> > jal preempt_schedule_irq
> > - b need_resched
> > + j restore_all
>
> One nit - why change from branch to jump? It's not a big deal, but I'd
> prefer we stick with the branch ("b") instruction for a few reasons:
>
> - restore_all is nearby so there's no issue with it being out of range
> of a branch in any variation of the MIPS ISA.
FYI, if it does go out of range for whatever reason, then for non-PIC
code GAS will relax it to a jump anyway (with a relocation attached); for
the regular MIPS ISA that is, where it has been doing that since forever
(I meant to implement this for the microMIPS ISA too, but IIRC there was a
complication there, probably coming from the existing more complex branch
relaxation code and/or slightly different use of relocations, and then it
fell through the cracks).
Maciej
next prev parent reply other threads:[~2019-05-10 16:16 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-11 22:47 [PATCH 00/14] entry: preempt_schedule_irq() callers scrub Valentin Schneider
2019-03-11 22:47 ` [PATCH 06/14] MIPS: entry: Remove unneeded need_resched() loop Valentin Schneider
2019-03-14 18:13 ` Paul Burton
2019-03-14 18:38 ` Valentin Schneider
2019-05-10 16:16 ` Maciej W. Rozycki [this message]
2019-03-15 16:31 ` [PATCH v2] " Valentin Schneider
2019-03-19 23:18 ` Paul Burton
2019-03-12 18:03 ` [PATCH 00/14] entry: preempt_schedule_irq() callers scrub Vineet Gupta
2019-03-12 18:18 ` Valentin Schneider
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