linux-kernel - Re: [PATCH 07/10] ARC: [plat-eznps] disabled stall counter due to a HW bug

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Message-ID: <1495710620.5393.29.camel@synopsys.com>
Date:   Thu, 25 May 2017 11:10:20 +0000
From:   Alexey Brodkin <Alexey.Brodkin@...opsys.com>
To:     "noamca@...lanox.com" <noamca@...lanox.com>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-snps-arc@...ts.infradead.org" 
        <linux-snps-arc@...ts.infradead.org>
Subject: Re: [PATCH 07/10] ARC: [plat-eznps] disabled stall counter due to a
 HW bug

Hi Noam,

On Thu, 2017-05-25 at 05:34 +0300, Noam Camus wrote:
> From: Noam Camus <noamca@...lanox.com>
> 
> This counter represents threshold for consecutive stall that which
> trigger HW threads scheduling.
> Low values of this counter cause downgrade in performance
> and in the worst case even a livelock.
> 
> Signed-off-by: Noam Camus <noamca@...lanox.com>
> ---
>  arch/arc/plat-eznps/mtm.c |    2 --
>  1 files changed, 0 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arc/plat-eznps/mtm.c b/arch/arc/plat-eznps/mtm.c
> index aaaaffd..e0cb36b 100644
> --- a/arch/arc/plat-eznps/mtm.c
> +++ b/arch/arc/plat-eznps/mtm.c
> @@ -119,8 +119,6 @@ void mtm_enable_core(unsigned int cpu)
>  	mt_ctrl.value = 0;
>  	mt_ctrl.hsen = 1;
>  	mt_ctrl.hs_cnt = MT_CTRL_HS_CNT;
> -	mt_ctrl.sten = 1;
> -	mt_ctrl.st_cnt = MT_CTRL_ST_CNT;

Even though I don't know your architecture this change doesn't
make enough sense to me in absence of better explanation of what is
really done here.

I.e. how removal of those 2 lines above improve your situation.

-Alexey