From: Tony Chuang <yhchuang@realtek.com>
To: Jian-Hong Pan <jian-hong@endlessm.com>
Cc: Kalle Valo <kvalo@codeaurora.org>,
"David S . Miller" <davem@davemloft.net>,
"linux-wireless@vger.kernel.org" <linux-wireless@vger.kernel.org>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux@endlessm.com" <linux@endlessm.com>,
Daniel Drake <drake@endlessm.com>,
"stable@vger.kernel.org" <stable@vger.kernel.org>
Subject: RE: [PATCH] rtw88/pci: Rearrange the memory usage for skb in RX ISR
Date: Mon, 8 Jul 2019 09:00:15 +0000 [thread overview]
Message-ID: <F7CD281DE3E379468C6D07993EA72F84D1861B71@RTITMBSVM04.realtek.com.tw> (raw)
In-Reply-To: <CAPpJ_eebQtL0y_j98J2T7m9g77A61SVtvD8qnNN42bV0dm4MLA@mail.gmail.com>
> > > @@ -803,25 +812,14 @@ static void rtw_pci_rx_isr(struct rtw_dev
> *rtwdev,
> > > struct rtw_pci *rtwpci,
> > > skb_put(skb, pkt_stat.pkt_len);
> > > skb_reserve(skb, pkt_offset);
> > >
> > > - /* alloc a smaller skb to mac80211 */
> > > - new = dev_alloc_skb(pkt_stat.pkt_len);
> > > - if (!new) {
> > > - new = skb;
> > > - } else {
> > > - skb_put_data(new, skb->data,
> skb->len);
> > > - dev_kfree_skb_any(skb);
> > > - }
> >
> > I am not sure if it's fine to deliver every huge SKB to mac80211.
> > Because it will then be delivered to TCP/IP stack.
> > Hence I think either it should be tested to know if the performance
> > would be impacted or find out a more efficient way to send
> > smaller SKB to mac80211 stack.
>
> I remember network stack only processes the skb with(in) pointers
> (skb->data) and the skb->len for data part. It also checks real
> buffer boundary (head and end) of the skb to prevent memory overflow.
> Therefore, I think using the original skb is the most efficient way.
>
> If I misunderstand something, please point out.
>
It means if we still use a huge SKB (~8K) for every RX packet (~1.5K).
There is about 6.5K not used. And even more if we ping with large packet
size "eg. $ ping -s 65536", I am not sure if those huge SKBs will eat all of
the SKB mem pool, and then ping fails.
BTW, the original design of RTK_PCI_RX_BUF_SIZE to be (8192 + 24) is to
receive AMSDU packet in one SKB.
(Could probably enlarge it to RX VHT AMSDU ~11K)
Yan-Hsuan
next prev parent reply other threads:[~2019-07-08 9:00 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-08 6:32 [PATCH] rtw88/pci: Rearrange the memory usage for skb in RX ISR Jian-Hong Pan
2019-07-08 7:23 ` Tony Chuang
2019-07-08 8:07 ` Jian-Hong Pan
2019-07-08 9:00 ` Tony Chuang [this message]
2019-07-08 9:18 ` David Laight
2019-07-08 8:36 ` David Laight
2019-07-08 18:01 ` Larry Finger
2019-07-09 10:20 ` [PATCH v2 1/2] rtw88: pci: " Jian-Hong Pan
2019-07-10 8:36 ` Tony Chuang
2019-07-10 8:54 ` Jian-Hong Pan
2019-07-09 10:21 ` [PATCH v2 2/2] rtw88: pci: Use DMA sync instead of remapping " Jian-Hong Pan
2019-07-09 16:15 ` Christoph Hellwig
2019-07-10 8:38 ` [PATCH v3 1/2] rtw88: pci: Rearrange the memory usage for skb " Jian-Hong Pan
2019-07-10 8:57 ` David Laight
2019-07-11 3:50 ` Jian-Hong Pan
2019-07-11 5:24 ` [PATCH v4 " Jian-Hong Pan
2019-07-11 5:24 ` [PATCH v4 2/2] rtw88: pci: Use DMA sync instead of remapping " Jian-Hong Pan
2019-07-11 5:30 ` Jian-Hong Pan
2019-07-11 5:28 ` [PATCH v4 1/2] rtw88: pci: Rearrange the memory usage for skb " Jian-Hong Pan
2019-07-24 6:13 ` Jian-Hong Pan
2019-07-24 11:49 ` Kalle Valo
2019-08-15 20:25 ` [PATCH v3 " Brian Norris
2019-07-10 8:38 ` [PATCH v3 2/2] rtw88: pci: Use DMA sync instead of remapping " Jian-Hong Pan
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=F7CD281DE3E379468C6D07993EA72F84D1861B71@RTITMBSVM04.realtek.com.tw \
--to=yhchuang@realtek.com \
--cc=davem@davemloft.net \
--cc=drake@endlessm.com \
--cc=jian-hong@endlessm.com \
--cc=kvalo@codeaurora.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-wireless@vger.kernel.org \
--cc=linux@endlessm.com \
--cc=netdev@vger.kernel.org \
--cc=stable@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).