netdev - Re: [PATCH net 1/3] bnxt_en: Fix accumulation of bp->net_stats

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Message-ID: <20200526150443.7a91ce77@kicinski-fedora-PC1C0HJN.hsd1.ca.comcast.net>
Date:   Tue, 26 May 2020 15:04:43 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     Michael Chan <michael.chan@...adcom.com>
Cc:     davem@...emloft.net, netdev@...r.kernel.org
Subject: Re: [PATCH net 1/3] bnxt_en: Fix accumulation of
 bp->net_stats_prev.

On Mon, 25 May 2020 17:41:17 -0400 Michael Chan wrote:
> We have logic to maintain network counters across resets by storing
> the counters in bp->net_stats_prev before reset.  But not all resets
> will clear the counters.  Certain resets that don't need to change
> the number of rings do not clear the counters.  The current logic
> accumulates the counters before all resets, causing big jumps in
> the counters after some resets, such as ethtool -G.
> 
> Fix it by only accumulating the counters during reset if the irq_re_init
> parameter is set.  The parameter signifies that all rings and interrupts
> will be reset and that means that the counters will also be reset.
> 
> Reported-by: Vijayendra Suman <vijayendra.suman@...cle.com>
> Fixes: b8875ca356f1 ("bnxt_en: Save ring statistics before reset.")
> Signed-off-by: Michael Chan <michael.chan@...adcom.com>

Hi Michael! 

Could you explain why accumulating counters causes a jump?