linux-kernel - Re: [PATCH net] rds: Fix incorrect statistics counting

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Message-ID: <6fb62a09-13b4-0cec-2864-40afdfc51d25@oracle.com>
Date:   Wed, 6 Sep 2017 09:21:01 -0700
From:   Santosh Shilimkar <santosh.shilimkar@...cle.com>
To:     Håkon Bugge <haakon.bugge@...cle.com>
Cc:     "David S . Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
        OFED mailing list <linux-rdma@...r.kernel.org>,
        rds-devel@....oracle.com, linux-kernel@...r.kernel.org,
        Knut Omang <knut.omang@...cle.com>
Subject: Re: [PATCH net] rds: Fix incorrect statistics counting

On 9/6/2017 9:12 AM, Håkon Bugge wrote:
> 
[...]

> 
> Hi Santosh,
> 
> 
> Yes, I agree with accuracy of s_send_lock_queue_raced. But the main point is that the existing code counts some partial share of when it is _not_ raced.
> 
> So, in the critical path, my patch adds one test_bit(), which hits the local CPU cache, if not raced. If raced, some other thread is in control, so I would not think the added cycles would make any big difference.
>
Cycles added for no good reason is the point.

> I can send a v2 where the race tightening is removed if you like.
> 
Yes please.

Regards,
Santosh