From: Kalle Valo <kvalo@codeaurora.org>
To: Wen Gong <wgong@codeaurora.org>
Cc: ath10k@lists.infradead.org, linux-wireless@vger.kernel.org
Subject: Re: [PATCH v6] ath10k: enable napi on RX path for sdio
Date: Thu, 31 Oct 2019 11:27:46 +0200 [thread overview]
Message-ID: <87tv7p1cz1.fsf@kamboji.qca.qualcomm.com> (raw)
In-Reply-To: <20191014114753.7459-1-wgong@codeaurora.org> (Wen Gong's message of "Mon, 14 Oct 2019 19:47:53 +0800")
Wen Gong <wgong@codeaurora.org> writes:
> For tcp RX, the quantity of tcp acks to remote is 1/2 of the quantity
> of tcp data from remote, then it will have many small length packets
> on TX path of sdio bus, then it reduce the RX packets's bandwidth of
> tcp.
>
> This patch enable napi on RX path, then the RX packet of tcp will not
> feed to tcp stack immeditely from mac80211 since GRO is enabled by
> default, it will feed to tcp stack after napi complete, if rx bundle
> is enabled, then it will feed to tcp stack one time for each bundle
> of RX. For example, RX bundle size is 32, then tcp stack will receive
> one large length packet, its length is neary 1500*32, then tcp stack
> will send a tcp ack for this large packet, this will reduce the tcp
> acks ratio from 1/2 to 1/32. This results in significant performance
> improvement for tcp RX.
>
> Tcp rx throughout is 240Mbps without this patch, and it arrive 390Mbps
> with this patch. The cpu usage has no obvious difference with and
> without NAPI.
I have not done thorough review yet, but few quick questions:
This adds a new skb queue ar->htt.rx_indication_head to RX path, but on
one of your earlier patches you also add another skb queue
ar_sdio->rx_head. Is it really necessary to have two separate queues in
RX path? Sounds like extra complexity to me.
The way I have understood that NAPI is used as a mechanism to disable
interrupts on the device and gain throughput from that. But in your
patch the poll function ath10k_sdio_napi_poll() doesn't touch the
hardware at all, it just processes packets from
ar->htt.rx_indication_head queue until budget runs out. I'm no NAPI
expert so I can't claim it's wrong, but at least it feels odd to me.
--
https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches
WARNING: multiple messages have this Message-ID (diff)
From: Kalle Valo <kvalo@codeaurora.org>
To: Wen Gong <wgong@codeaurora.org>
Cc: linux-wireless@vger.kernel.org, ath10k@lists.infradead.org
Subject: Re: [PATCH v6] ath10k: enable napi on RX path for sdio
Date: Thu, 31 Oct 2019 11:27:46 +0200 [thread overview]
Message-ID: <87tv7p1cz1.fsf@kamboji.qca.qualcomm.com> (raw)
In-Reply-To: <20191014114753.7459-1-wgong@codeaurora.org> (Wen Gong's message of "Mon, 14 Oct 2019 19:47:53 +0800")
Wen Gong <wgong@codeaurora.org> writes:
> For tcp RX, the quantity of tcp acks to remote is 1/2 of the quantity
> of tcp data from remote, then it will have many small length packets
> on TX path of sdio bus, then it reduce the RX packets's bandwidth of
> tcp.
>
> This patch enable napi on RX path, then the RX packet of tcp will not
> feed to tcp stack immeditely from mac80211 since GRO is enabled by
> default, it will feed to tcp stack after napi complete, if rx bundle
> is enabled, then it will feed to tcp stack one time for each bundle
> of RX. For example, RX bundle size is 32, then tcp stack will receive
> one large length packet, its length is neary 1500*32, then tcp stack
> will send a tcp ack for this large packet, this will reduce the tcp
> acks ratio from 1/2 to 1/32. This results in significant performance
> improvement for tcp RX.
>
> Tcp rx throughout is 240Mbps without this patch, and it arrive 390Mbps
> with this patch. The cpu usage has no obvious difference with and
> without NAPI.
I have not done thorough review yet, but few quick questions:
This adds a new skb queue ar->htt.rx_indication_head to RX path, but on
one of your earlier patches you also add another skb queue
ar_sdio->rx_head. Is it really necessary to have two separate queues in
RX path? Sounds like extra complexity to me.
The way I have understood that NAPI is used as a mechanism to disable
interrupts on the device and gain throughput from that. But in your
patch the poll function ath10k_sdio_napi_poll() doesn't touch the
hardware at all, it just processes packets from
ar->htt.rx_indication_head queue until budget runs out. I'm no NAPI
expert so I can't claim it's wrong, but at least it feels odd to me.
--
https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches
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next prev parent reply other threads:[~2019-10-31 9:27 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-14 11:47 [PATCH v6] ath10k: enable napi on RX path for sdio Wen Gong
2019-10-14 11:47 ` Wen Gong
2019-10-25 13:13 ` Kalle Valo
2019-10-25 13:13 ` Kalle Valo
2019-10-31 9:27 ` Kalle Valo [this message]
2019-10-31 9:27 ` Kalle Valo
2019-11-01 8:00 ` Wen Gong
2019-11-01 8:00 ` Wen Gong
2019-12-02 10:00 ` Kalle Valo
2019-12-02 10:00 ` Kalle Valo
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