From: Peter Zijlstra <peterz@infradead.org>
To: Noam Camus <noamc@ezchip.com>
Cc: linux-snps-arc@lists.infradead.org, linux-kernel@vger.kernel.org,
talz@ezchip.com, gilf@ezchip.com, cmetcalf@ezchip.com
Subject: Re: [PATCH v1 16/20] ARC: [plat-eznps] Use dedicated cpu_relax()
Date: Mon, 2 Nov 2015 10:21:42 +0100 [thread overview]
Message-ID: <20151102092142.GL17308@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <1446297327-16298-17-git-send-email-noamc@ezchip.com>
On Sat, Oct 31, 2015 at 03:15:23PM +0200, Noam Camus wrote:
> From: Tal Zilcer <talz@ezchip.com>
>
> Since the CTOP is SMT hardware multi-threaded, we need to hint
> the HW that now will be a very good time to do a hardware
> thread context switching. This is done by issuing the schd.rw
> instruction (binary coded here so as to not require specific
> revision of GCC to build the kernel).
> sched.rw means that Thread becomes eligible for execution by
> the threads scheduler after all pending read/write
> transactions were completed.
>
> Signed-off-by: Noam Camus <noamc@ezchip.com>
> Cc: Peter Zijlstra <peterz@infradead.org>
> ---
> arch/arc/include/asm/processor.h | 5 +++++
> 1 files changed, 5 insertions(+), 0 deletions(-)
>
> diff --git a/arch/arc/include/asm/processor.h b/arch/arc/include/asm/processor.h
> index 7266ede..f1a51a6 100644
> --- a/arch/arc/include/asm/processor.h
> +++ b/arch/arc/include/asm/processor.h
> @@ -58,7 +58,12 @@ struct task_struct;
> * get optimised away by gcc
> */
> #ifdef CONFIG_SMP
> +#ifdef CONFIG_EZNPS_MTM_EXT
> +#define cpu_relax() \
> + __asm__ __volatile__ (".word %0" : : "i"(CTOP_INST_SCHD_RW) : "memory")
> +#else
> #define cpu_relax() __asm__ __volatile__ ("" : : : "memory")
> +#endif
> #else
> #define cpu_relax() do { } while (0)
> #endif
At which point you might want to revisit:
arch/arc/include/asm/processor.h:#define cpu_relax_lowlatency() cpu_relax()
next prev parent reply other threads:[~2015-11-02 9:21 UTC|newest]
Thread overview: 95+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-31 13:15 [PATCH v1 00/20] eznps a new ARC platform Noam Camus
2015-10-31 13:15 ` [PATCH v1 01/20] Documentation: Add EZchip vendor to binding list Noam Camus
2015-10-31 13:15 ` [PATCH v1 02/20] clocksource: Add NPS400 timers driver Noam Camus
2015-11-01 20:44 ` Daniel Lezcano
2015-11-02 7:57 ` Noam Camus
2015-11-02 11:03 ` Vineet Gupta
2015-11-03 15:18 ` Noam Camus
2015-10-31 13:15 ` [PATCH v1 03/20] irqchip: add nps Internal and external irqchips Noam Camus
2015-10-31 13:15 ` [PATCH v1 04/20] ARC: Set vmalloc size from configuration Noam Camus
2015-10-31 13:15 ` [PATCH v1 05/20] ARC: rwlock: disable interrupts in !LLSC variant Noam Camus
2015-11-02 9:16 ` Peter Zijlstra
2015-11-02 9:42 ` Vineet Gupta
2015-11-02 10:03 ` Peter Zijlstra
2015-10-31 13:15 ` [PATCH v1 06/20] ARC: Mark cpu online only after it has executed the per cpu init hook Noam Camus
2015-10-31 13:15 ` [PATCH v1 07/20] ARC: mm: use generic macros _BITUL() Noam Camus
2015-11-02 6:23 ` Vineet Gupta
2015-11-02 6:27 ` Noam Camus
2015-10-31 13:15 ` [PATCH v1 08/20] ARC: Use res_service as entry point for secondaries Noam Camus
2015-11-02 6:38 ` Vineet Gupta
2015-11-02 8:05 ` Noam Camus
2015-10-31 13:15 ` [PATCH v1 09/20] ARC: add CONFIG_CLKSRC_OF support to time_init() Noam Camus
2015-11-02 6:32 ` Vineet Gupta
2015-10-31 13:15 ` [PATCH v1 10/20] ARC: [plat-eznps] Add eznps board defconfig and dts Noam Camus
2015-10-31 13:15 ` [PATCH v1 11/20] ARC: [plat-eznps] Add eznps platform Noam Camus
2015-11-02 10:56 ` Vineet Gupta
2015-11-03 15:59 ` Noam Camus
2015-11-04 12:38 ` Noam Camus
2015-11-05 5:09 ` Vineet Gupta
2015-10-31 13:15 ` [PATCH v1 12/20] ARC: [plat-eznps] Use dedicated user stack top Noam Camus
2015-10-31 13:15 ` [PATCH v1 13/20] ARC: [plat-eznps] Use dedicated bitops/atomic/cmpxchg Noam Camus
2015-11-02 11:56 ` Vineet Gupta
2015-10-31 13:15 ` [PATCH v1 14/20] ARC: [plat-eznps] Use dedicated SMP barriers Noam Camus
2015-11-02 8:02 ` Vineet Gupta
2015-11-02 13:08 ` Noam Camus
2015-10-31 13:15 ` [PATCH v1 15/20] ARC: [plat-eznps] Use dedicated identity auxiliary register Noam Camus
2015-10-31 13:15 ` [PATCH v1 16/20] ARC: [plat-eznps] Use dedicated cpu_relax() Noam Camus
2015-11-02 7:54 ` Vineet Gupta
2015-11-02 9:21 ` Peter Zijlstra [this message]
2015-11-03 14:02 ` Noam Camus
2015-10-31 13:15 ` [PATCH v1 17/20] ARC: [plat-eznps] Use dedicated COMMAND_LINE_SIZE Noam Camus
2015-10-31 13:15 ` [PATCH v1 18/20] ARC: [plat-eznps] define IPI_IRQ Noam Camus
2015-11-02 7:52 ` Vineet Gupta
2015-11-02 12:16 ` Noam Camus
2015-10-31 13:15 ` [PATCH v1 19/20] ARC: [plat-eznps] replace sync with proper cpu barrier Noam Camus
2015-11-02 7:48 ` Vineet Gupta
2015-11-02 9:26 ` Peter Zijlstra
2015-11-17 13:48 ` [PATCH] ARC: remove SYNC from __switch_to() Vineet Gupta
2015-10-31 13:15 ` [PATCH v1 20/20] ARC: Add eznps platform to Kconfig and Makefile Noam Camus
2015-11-02 11:06 ` Vineet Gupta
2015-11-03 15:32 ` Noam Camus
2015-11-04 15:35 ` [PATCH v1 00/20] eznps a new ARC platform Vineet Gupta
2015-11-04 15:53 ` Noam Camus
2015-11-04 17:42 ` Vineet Gupta
2015-11-07 10:52 ` [PATCH v2 00/19] " Noam Camus
2015-11-07 10:52 ` [PATCH v2 01/19] Documentation: Add EZchip vendor to binding list Noam Camus
2015-11-07 10:52 ` [PATCH v2 02/19] ARC: [plat-eznps] define IPI_IRQ Noam Camus
2015-11-07 10:52 ` [PATCH v2 03/19] clocksource: Add NPS400 timers driver Noam Camus
2015-11-07 11:26 ` Thomas Gleixner
2015-11-20 11:59 ` Noam Camus
2015-11-07 10:52 ` [PATCH v2 04/19] irqchip: add nps Internal and external irqchips Noam Camus
2015-11-07 11:38 ` Thomas Gleixner
2015-11-07 20:52 ` Noam Camus
2015-11-07 23:52 ` Thomas Gleixner
2015-11-07 10:52 ` [PATCH v2 05/19] ARC: Set vmalloc size from configuration Noam Camus
2015-11-07 10:52 ` [PATCH v2 06/19] ARC: rwlock: disable interrupts in !LLSC variant Noam Camus
2015-11-07 10:52 ` [PATCH v2 07/19] ARC: rename smp operation init_irq_cpu() to init_per_cpu() Noam Camus
2015-11-17 11:15 ` Vineet Gupta
2015-11-17 11:38 ` Noam Camus
2015-11-17 11:42 ` Vineet Gupta
2015-11-07 10:52 ` [PATCH v2 08/19] ARC: Mark secondary cpu online only after all HW setup is done Noam Camus
2015-11-17 11:17 ` Vineet Gupta
2015-11-07 10:52 ` [PATCH v2 09/19] ARC: add CONFIG_CLKSRC_OF support to time_init() Noam Camus
2015-11-07 10:52 ` [PATCH v2 10/19] ARC: [plat-eznps] Add eznps board defconfig and dts Noam Camus
2015-11-07 10:52 ` [PATCH v2 11/19] ARC: [plat-eznps] Add eznps platform Noam Camus
2015-11-07 10:52 ` [PATCH v2 12/19] ARC: [plat-eznps] Use dedicated user stack top Noam Camus
2015-11-07 10:52 ` [PATCH v2 13/19] ARC: [plat-eznps] Use dedicated atomic/bitops/cmpxchg Noam Camus
2015-11-07 10:52 ` [PATCH v2 14/19] ARC: [plat-eznps] Use dedicated SMP barriers Noam Camus
2015-11-07 10:52 ` [PATCH v2 15/19] ARC: [plat-eznps] Use dedicated identity auxiliary register Noam Camus
2015-11-07 10:52 ` [PATCH v2 16/19] ARC: [plat-eznps] Use dedicated cpu_relax() Noam Camus
2015-11-09 10:05 ` Peter Zijlstra
2015-11-09 10:22 ` Vineet Gupta
2015-11-09 10:45 ` Peter Zijlstra
2015-11-09 12:27 ` Vineet Gupta
2015-11-09 12:51 ` Peter Zijlstra
2015-11-07 10:52 ` [PATCH v2 17/19] ARC: [plat-eznps] Use dedicated COMMAND_LINE_SIZE Noam Camus
2015-11-07 10:52 ` [PATCH v2 18/19] ARC: [plat-eznps] replace sync with proper cpu barrier Noam Camus
2015-11-17 11:12 ` Vineet Gupta
2015-11-17 11:23 ` Peter Zijlstra
2015-11-17 11:37 ` Vineet Gupta
2015-11-17 12:22 ` Peter Zijlstra
2015-11-17 12:37 ` Vineet Gupta
2015-11-17 12:44 ` Peter Zijlstra
2015-11-17 13:32 ` Vineet Gupta
2015-11-17 13:59 ` Peter Zijlstra
2015-11-07 10:52 ` [PATCH v2 19/19] ARC: Add eznps platform to Kconfig and Makefile Noam Camus
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