From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: "Philippe Mathieu-Daudé" <philmd@linaro.org>, qemu-devel@nongnu.org
Cc: Bernhard Beschow <shentey@gmail.com>,
Nicholas Piggin <npiggin@gmail.com>,
bharata.rao@gmail.com, Chinmay Rath <rathc@linux.ibm.com>,
qemu-ppc@nongnu.org
Subject: Re: [PATCH 2/3] target/ppc: Have gen_pause() actually pause vCPUs
Date: Tue, 30 Sep 2025 08:59:12 +1000 [thread overview]
Message-ID: <5923fc8c7ac36d8bcae7a416cfd072c18c8698ec.camel@kernel.crashing.org> (raw)
In-Reply-To: <8099d09f-029d-4562-b035-7b832ac27ccc@linaro.org>
On Mon, 2025-09-29 at 09:51 +0200, Philippe Mathieu-Daudé wrote:
> > What will resume it though ? The smt_low() case isn't meant to
> > *halt*
> > the CPUs permanently. smt_*() levels are about SMT thread
> > priorities.
> > Using a "pause" that just gets out of TCG (and back in), is a way
> > to
> > "yield" to another thread, thus enabling more forward progress when
> > a
>
> What you describe can be achieved with a helper doing:
>
> cs->exception_index = EXCP_YIELD;
> cpu_loop_exit(cs);
>
> Is that what you wanted?
I suppose so... this was many years ago and I don't have much context
anymore, so I don't know why I didn't do it that way back then.
Cheers,
Ben.
next prev parent reply other threads:[~2025-09-29 23:00 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-24 17:30 [PATCH 0/3] target/ppc: Have gen_pause() actually pause vCPUs Philippe Mathieu-Daudé
2025-09-24 17:30 ` [PATCH 1/3] hw/ppc: Do not open-code cpu_resume() in spin_kick() Philippe Mathieu-Daudé
2025-09-24 17:58 ` Richard Henderson
2025-09-24 17:30 ` [PATCH 2/3] target/ppc: Have gen_pause() actually pause vCPUs Philippe Mathieu-Daudé
2025-09-24 17:58 ` Richard Henderson
2025-09-29 4:28 ` Benjamin Herrenschmidt
2025-09-29 7:51 ` Philippe Mathieu-Daudé
2025-09-29 22:59 ` Benjamin Herrenschmidt [this message]
2025-09-30 3:00 ` Philippe Mathieu-Daudé
2025-09-24 17:30 ` [PATCH 3/3] target/ppc: Re-use gen_pause() in gen_wait() Philippe Mathieu-Daudé
2025-09-24 18:05 ` Richard Henderson
2025-10-07 8:21 ` [PATCH 0/3] target/ppc: Have gen_pause() actually pause vCPUs Philippe Mathieu-Daudé
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