linux-kernel - Re: [PATCH 11/14] staging/lustre/ptlrpc: Correctly calculate hrp->hrp

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Date:   Mon, 7 Nov 2016 01:58:17 +0000 (GMT)
From:   James Simmons <jsimmons@...radead.org>
To:     Oleg Drokin <green@...uxhacker.ru>
cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        devel@...verdev.osuosl.org,
        Andreas Dilger <andreas.dilger@...el.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Lustre Development List <lustre-devel@...ts.lustre.org>,
        Amir Shehata <amir.shehata@...el.com>
Subject: Re: [PATCH 11/14] staging/lustre/ptlrpc: Correctly calculate
 hrp->hrp_nthrs

On Wed, 2 Nov 2016, Oleg Drokin wrote:

> From: Amir Shehata <amir.shehata@...el.com>
> 
> cpu_pattern can specify exactly 1 cpu in a partition:
> "0[0]". That means CPT0 will have CPU 0. CPU 0 can have
> hyperthreading enabled. This combination would result in
> 
> weight = cfs_cpu_ht_nsiblings(0);
> hrp->hrp_nthrs = cfs_cpt_weight(ptlrpc_hr.hr_cpt_table, i);
> hrp->hrp_nthrs /= weight;
> 
> evaluating to 0. Where
> cfs_cpt_weight(ptlrpc_hr.hr_cpt_table, i) == 1
> weight == 2
> 
> Therefore, if hrp_nthrs becomes zero, just set it to 1.

Reviewed-by: James Simmons <jsimmons@...radead.org>
 
> Signed-off-by: Amir Shehata <amir.shehata@...el.com>
> Reviewed-on: http://review.whamcloud.com/19106
> Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-8492
> Reviewed-by: Liang Zhen <liang.zhen@...el.com>
> Reviewed-by: Doug Oucharek <doug.s.oucharek@...el.com>
> Reviewed-by: James Simmons <uja.ornl@...oo.com>
> Signed-off-by: Oleg Drokin <green@...uxhacker.ru>
> ---
>  drivers/staging/lustre/lustre/ptlrpc/service.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/staging/lustre/lustre/ptlrpc/service.c b/drivers/staging/lustre/lustre/ptlrpc/service.c
> index 72f3930..fc754e7 100644
> --- a/drivers/staging/lustre/lustre/ptlrpc/service.c
> +++ b/drivers/staging/lustre/lustre/ptlrpc/service.c
> @@ -2541,8 +2541,9 @@ int ptlrpc_hr_init(void)
>  
>  		hrp->hrp_nthrs = cfs_cpt_weight(ptlrpc_hr.hr_cpt_table, i);
>  		hrp->hrp_nthrs /= weight;
> +		if (hrp->hrp_nthrs == 0)
> +			hrp->hrp_nthrs = 1;
>  
> -		LASSERT(hrp->hrp_nthrs > 0);
>  		hrp->hrp_thrs =
>  			kzalloc_node(hrp->hrp_nthrs * sizeof(*hrt), GFP_NOFS,
>  				     cfs_cpt_spread_node(ptlrpc_hr.hr_cpt_table,
> -- 
> 2.7.4
> 
>