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From: Eric Dumazet <eric.dumazet@gmail.com>
To: Yidong Ren <yidren@linuxonhyperv.com>,
	"K. Y. Srinivasan" <kys@microsoft.com>,
	Haiyang Zhang <haiyangz@microsoft.com>,
	Stephen Hemminger <sthemmin@microsoft.com>,
	"David S. Miller" <davem@davemloft.net>,
	devel@linuxdriverproject.org, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org
Cc: Yidong Ren <yidren@microsoft.com>
Subject: Re: [PATCH v2] hv_netvsc: Add per-cpu ethtool stats for netvsc
Date: Wed, 13 Jun 2018 13:57:33 -0700	[thread overview]
Message-ID: <4c853799-44e0-ff33-3555-41982d601ebb@gmail.com> (raw)
In-Reply-To: <20180613193608.444-1-yidren@linuxonhyperv.com>



On 06/13/2018 12:36 PM, Yidong Ren wrote:
> From: Yidong Ren <yidren@microsoft.com>
> 
> This patch implements following ethtool stats fields for netvsc:
> cpu<n>_tx/rx_packets/bytes
> cpu<n>_vf_tx/rx_packets/bytes

...
>  
> +	pcpu_sum = alloc_percpu(struct netvsc_ethtool_pcpu_stats);
> +	netvsc_get_pcpu_stats(dev, pcpu_sum);
> +	for_each_present_cpu(cpu) {
> +		struct netvsc_ethtool_pcpu_stats *this_sum =
> +			per_cpu_ptr(pcpu_sum, cpu);
> +		for (j = 0; j < ARRAY_SIZE(pcpu_stats); j++)
> +			data[i++] = *(u64 *)((void *)this_sum
> +					     + pcpu_stats[j].offset);
> +	}
> +	free_percpu(pcpu_sum);
>


Using alloc_percpu() / free_percpu() for a short section of code makes no sense.

You actually want to allocate memory local to this cpu, possibly in one chunk,
not spread all over the places.

kvmalloc(nr_cpu_ids * sizeof(struct netvsc_ethtool_pcpu_stats))  should be really better,
since it would most of the time be satisfied by a single kmalloc()


WARNING: multiple messages have this Message-ID (diff)
From: Eric Dumazet <eric.dumazet@gmail.com>
To: Yidong Ren <yidren@linuxonhyperv.com>,
	"K. Y. Srinivasan" <kys@microsoft.com>,
	Haiyang Zhang <haiyangz@microsoft.com>,
	Stephen Hemminger <sthemmin@microsoft.com>,
	"David S. Miller" <davem@davemloft.net>,
	devel@linuxdriverproject.org, netdev@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] hv_netvsc: Add per-cpu ethtool stats for netvsc
Date: Wed, 13 Jun 2018 13:57:33 -0700	[thread overview]
Message-ID: <4c853799-44e0-ff33-3555-41982d601ebb@gmail.com> (raw)
In-Reply-To: <20180613193608.444-1-yidren@linuxonhyperv.com>



On 06/13/2018 12:36 PM, Yidong Ren wrote:
> From: Yidong Ren <yidren@microsoft.com>
> 
> This patch implements following ethtool stats fields for netvsc:
> cpu<n>_tx/rx_packets/bytes
> cpu<n>_vf_tx/rx_packets/bytes

...
>  
> +	pcpu_sum = alloc_percpu(struct netvsc_ethtool_pcpu_stats);
> +	netvsc_get_pcpu_stats(dev, pcpu_sum);
> +	for_each_present_cpu(cpu) {
> +		struct netvsc_ethtool_pcpu_stats *this_sum =
> +			per_cpu_ptr(pcpu_sum, cpu);
> +		for (j = 0; j < ARRAY_SIZE(pcpu_stats); j++)
> +			data[i++] = *(u64 *)((void *)this_sum
> +					     + pcpu_stats[j].offset);
> +	}
> +	free_percpu(pcpu_sum);
>


Using alloc_percpu() / free_percpu() for a short section of code makes no sense.

You actually want to allocate memory local to this cpu, possibly in one chunk,
not spread all over the places.

kvmalloc(nr_cpu_ids * sizeof(struct netvsc_ethtool_pcpu_stats))  should be really better,
since it would most of the time be satisfied by a single kmalloc()

  reply	other threads:[~2018-06-13 20:57 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-06-13 19:36 [PATCH v2] hv_netvsc: Add per-cpu ethtool stats for netvsc Yidong Ren
2018-06-13 19:36 ` Yidong Ren
2018-06-13 20:57 ` Eric Dumazet [this message]
2018-06-13 20:57   ` Eric Dumazet
2018-06-13 21:07   ` Yidong Ren
2018-06-13 21:48 ` Stephen Hemminger
2018-06-13 22:03   ` Yidong Ren
2018-06-13 22:18     ` Stephen Hemminger
2018-07-24  1:26 ` [PATCH v3] " Yidong Ren
2018-07-24  1:26   ` Yidong Ren
2018-07-24  1:42   ` Yidong Ren
2018-07-24 11:00     ` Vitaly Kuznetsov
2018-07-24 11:00       ` Vitaly Kuznetsov
2018-07-25 22:54       ` Yidong Ren
2018-07-25 22:54         ` Yidong Ren
2018-07-30 17:09   ` [PATCH v4 net-next] " Yidong Ren
2018-07-30 17:34     ` Stephen Hemminger
2018-07-30 19:34     ` David Miller

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