From: Jakub Kicinski <kuba@kernel.org>
To: Alexander Lobakin <aleksander.lobakin@intel.com>
Cc: Edward Cree <ecree.xilinx@gmail.com>, <davem@davemloft.net>,
<netdev@vger.kernel.org>, <edumazet@google.com>,
<pabeni@redhat.com>, <willemb@google.com>, <fw@strlen.de>
Subject: Re: [PATCH net-next 2/3] net: skbuff: cache one skb_ext for use by GRO
Date: Wed, 15 Feb 2023 10:20:15 -0800 [thread overview]
Message-ID: <20230215102015.70d81a20@kernel.org> (raw)
In-Reply-To: <4aa71029-8a4a-0c6d-438d-71cebb11ccea@intel.com>
On Wed, 15 Feb 2023 19:01:19 +0100 Alexander Lobakin wrote:
> > I was hoping to leave sizing of the cache until we have some data from
> > a production network (or at least representative packet traces).
> >
> > NAPI_SKB_CACHE_SIZE kinda assumes we're not doing much GRO, right?
>
> It assumes we GRO a lot :D
>
> Imagine that you have 64 frames during one poll and the GRO layer
> decides to coalesce them by batches of 16. Then only 4 skbs will be
> used, the rest will go as frags (with "stolen heads") -> 60 of 64 skbs
> will return to that skb cache and will then be reused by napi_build_skb().
Let's say 5 - for 4 resulting skbs GRO will need the 4 resulting and
one extra to shuttle between the driver and GRO (worst case).
With a cache of 1 I'm guaranteed to save 59 alloc calls, 92%, right?
That's why I'm saying - the larger cache would help workloads which
don't GRO as much. Am I missing the point or how GRO works?
next prev parent reply other threads:[~2023-02-15 18:20 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-15 3:43 [PATCH net-next 0/3] net: skbuff: cache one skb_ext for use by GRO Jakub Kicinski
2023-02-15 3:43 ` [PATCH net-next 1/3] net: skb: carve the allocation out of skb_ext_add() Jakub Kicinski
2023-02-15 3:43 ` [PATCH net-next 2/3] net: skbuff: cache one skb_ext for use by GRO Jakub Kicinski
2023-02-15 8:41 ` Paolo Abeni
2023-02-15 17:45 ` Jakub Kicinski
2023-02-15 18:08 ` Alexander Lobakin
2023-02-15 19:08 ` Paolo Abeni
2023-02-15 15:37 ` Edward Cree
2023-02-15 16:17 ` Alexander Lobakin
2023-02-15 17:52 ` Jakub Kicinski
2023-02-15 18:01 ` Alexander Lobakin
2023-02-15 18:20 ` Jakub Kicinski [this message]
2023-02-16 12:04 ` Alexander Lobakin
2023-02-15 3:43 ` [PATCH net-next 3/3] net: create and use NAPI version of tc_skb_ext_alloc() Jakub Kicinski
2023-02-15 16:50 ` Jamal Hadi Salim
2023-02-15 17:03 ` Jiri Pirko
2023-02-15 18:36 ` Jamal Hadi Salim
2023-02-15 17:35 ` Jakub Kicinski
2023-02-15 18:38 ` Jamal Hadi Salim
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=20230215102015.70d81a20@kernel.org \
--to=kuba@kernel.org \
--cc=aleksander.lobakin@intel.com \
--cc=davem@davemloft.net \
--cc=ecree.xilinx@gmail.com \
--cc=edumazet@google.com \
--cc=fw@strlen.de \
--cc=netdev@vger.kernel.org \
--cc=pabeni@redhat.com \
--cc=willemb@google.com \
/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).