From: Marc Zyngier <maz@kernel.org>
To: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Will Deacon <will@kernel.org>,
Suleiman Souhlal <suleiman@google.com>,
Joel Fernandes <joelaf@google.com>,
linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org
Subject: Re: [PATCHv2 3/4] arm64: do not use dummy vcpu_is_preempted()
Date: Mon, 12 Jul 2021 16:47:03 +0100 [thread overview]
Message-ID: <875yxf356w.wl-maz@kernel.org> (raw)
In-Reply-To: <20210709043713.887098-4-senozhatsky@chromium.org>
On Fri, 09 Jul 2021 05:37:12 +0100,
Sergey Senozhatsky <senozhatsky@chromium.org> wrote:
>
> vcpu_is_preempted() now can represent the actual state of
> the VCPU, so the scheduler can make better decisions when
> it picks the idle CPU to enqueue a task on.
>
> Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org>
> ---
> arch/arm64/include/asm/spinlock.h | 18 ++++++++++--------
> 1 file changed, 10 insertions(+), 8 deletions(-)
>
> diff --git a/arch/arm64/include/asm/spinlock.h b/arch/arm64/include/asm/spinlock.h
> index 0525c0b089ed..1d579497e1b8 100644
> --- a/arch/arm64/include/asm/spinlock.h
> +++ b/arch/arm64/include/asm/spinlock.h
> @@ -7,21 +7,23 @@
>
> #include <asm/qspinlock.h>
> #include <asm/qrwlock.h>
> +#include <asm/paravirt.h>
>
> /* See include/linux/spinlock.h */
> #define smp_mb__after_spinlock() smp_mb()
>
> -/*
> - * Changing this will break osq_lock() thanks to the call inside
> - * smp_cond_load_relaxed().
> - *
> - * See:
> - * https://lore.kernel.org/lkml/20200110100612.GC2827@hirez.programming.kicks-ass.net
> - */
Why are you deleting this? Please explain your reasoning in the commit
message. It seems to me that it still makes complete sense when
CONFIG_PARAVIRT is not defined.
> #define vcpu_is_preempted vcpu_is_preempted
> -static inline bool vcpu_is_preempted(int cpu)
> +
> +#ifdef CONFIG_PARAVIRT
> +static inline bool vcpu_is_preempted(unsigned int cpu)
> +{
> + return paravirt_vcpu_is_preempted(cpu);
> +}
> +#else
> +static inline bool vcpu_is_preempted(unsigned int cpu)
> {
> return false;
> }
> +#endif /* CONFIG_PARAVIRT */
>
> #endif /* __ASM_SPINLOCK_H */
Thanks,
M.
--
Without deviation from the norm, progress is not possible.
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2021-07-12 15:48 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-09 4:37 [PATCHv2 0/4] arm64:kvm: teach guest sched that VCPUs can be preempted Sergey Senozhatsky
2021-07-09 4:37 ` [PATCHv2 1/4] arm64: smccc: Add SMCCC pv-vcpu-state function call IDs Sergey Senozhatsky
2021-07-12 14:22 ` Marc Zyngier
2021-07-09 4:37 ` [PATCHv2 2/4] arm64: add guest pvstate support Sergey Senozhatsky
2021-07-09 7:39 ` David Edmondson
2021-07-09 7:52 ` Sergey Senozhatsky
2021-07-09 18:58 ` Joel Fernandes
2021-07-09 21:53 ` Sergey Senozhatsky
2021-07-11 16:58 ` Joel Fernandes
2021-07-12 15:42 ` Marc Zyngier
2021-07-21 2:05 ` Sergey Senozhatsky
2021-07-21 8:22 ` Marc Zyngier
2021-07-21 8:47 ` Sergey Senozhatsky
2021-07-21 10:16 ` Marc Zyngier
2021-07-09 4:37 ` [PATCHv2 3/4] arm64: do not use dummy vcpu_is_preempted() Sergey Senozhatsky
2021-07-12 15:47 ` Marc Zyngier [this message]
2021-07-21 2:06 ` Sergey Senozhatsky
2021-07-09 4:37 ` [PATCHv2 4/4] arm64: add host pv-vcpu-state support Sergey Senozhatsky
2021-07-12 16:24 ` Marc Zyngier
2021-07-20 18:44 ` Joel Fernandes
2021-07-21 8:40 ` Marc Zyngier
2021-07-21 10:38 ` Sergey Senozhatsky
2021-07-21 11:08 ` Marc Zyngier
2021-07-21 1:15 ` Sergey Senozhatsky
2021-07-21 9:10 ` Marc Zyngier
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=875yxf356w.wl-maz@kernel.org \
--to=maz@kernel.org \
--cc=joelaf@google.com \
--cc=kvmarm@lists.cs.columbia.edu \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=senozhatsky@chromium.org \
--cc=suleiman@google.com \
--cc=virtualization@lists.linux-foundation.org \
--cc=will@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).