linux-kernel - RE: [PATCH v4] Drivers: hv: vmbus: Expose counters for interrupts and full conditions

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Message-ID: <DM5PR2101MB091863AD0DEF25395352BF98D76D0@DM5PR2101MB0918.namprd21.prod.outlook.com>
Date:   Mon, 4 Feb 2019 16:25:34 +0000
From:   Michael Kelley <mikelley@...rosoft.com>
To:     kimbrownkd <kimbrownkd@...il.com>, Long Li <longli@...rosoft.com>,
        Sasha Levin <Alexander.Levin@...rosoft.com>,
        Dexuan Cui <decui@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>
CC:     KY Srinivasan <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        "devel@...uxdriverproject.org" <devel@...uxdriverproject.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v4] Drivers: hv: vmbus: Expose counters for interrupts and
 full conditions

From: Kimberly Brown <kimbrownkd@...il.com> Sent: Sunday, February 3, 2019 11:13 PM
> 
> Counter values for per-channel interrupts and ring buffer full
> conditions are useful for investigating performance.
> 
> Expose counters in sysfs for 2 types of guest to host interrupts:
> 1) Interrupts caused by the channel's outbound ring buffer transitioning
> from empty to not empty
> 2) Interrupts caused by the channel's inbound ring buffer transitioning
> from full to not full while a packet is waiting for enough buffer space to
> become available
> 
> Expose 2 counters in sysfs for the number of times that write operations
> encountered a full outbound ring buffer:
> 1) The total number of write operations that encountered a full
> condition
> 2) The number of write operations that were the first to encounter a
> full condition
> 
> Increment the outbound full condition counters in the
> hv_ringbuffer_write() function because, for most drivers, a full
> outbound ring buffer is detected in that function. Also increment the
> outbound full condition counters in the set_channel_pending_send_size()
> function. In the hv_sock driver, a full outbound ring buffer is detected
> and set_channel_pending_send_size() is called before
> hv_ringbuffer_write() is called.
> 
> I tested this patch by confirming that the sysfs files were created and
> observing the counter values. The values seemed to increase by a
> reasonable amount when the Hyper-v related drivers were in use.
> 
> Signed-off-by: Kimberly Brown <kimbrownkd@...il.com>
> ---
> 
Reviewed-by:  Michael Kelley <mikelley@...rosoft.com>