netdev - [RFC net-next v2 0/3] page_pool: allow caching from safely localized NAPI

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Message-Id: <20230405232100.103392-1-kuba@kernel.org>
Date:   Wed,  5 Apr 2023 16:20:57 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     davem@...emloft.net
Cc:     netdev@...r.kernel.org, edumazet@...gle.com, pabeni@...hat.com,
        hawk@...nel.org, ilias.apalodimas@...aro.org,
        Jakub Kicinski <kuba@...nel.org>
Subject: [RFC net-next v2 0/3] page_pool: allow caching from safely localized NAPI

I went back to the explicit "are we in NAPI method", mostly
because I don't like having both around :( (even tho I maintain
that in_softirq() && !in_hardirq() is as safe, as softirqs do
not nest).

Still returning the skbs to a CPU, tho, not to the NAPI instance.
I reckon we could create a small refcounted struct per NAPI instance
which would allow sockets and other users so hold a persisent
and safe reference. But that's a bigger change, and I get 90+%
recycling thru the cache with just these patches (for RR and
streaming tests with 100% CPU use it's almost 100%).

Some numbers for streaming test with 100% CPU use (from previous version,
but really they perform the same):

		HW-GRO				page=page
		before		after		before		after
recycle:
cached:			0	138669686		0	150197505
cache_full:		0	   223391		0	    74582
ring:		138551933         9997191	149299454		0
ring_full: 		0             488	     3154	   127590
released_refcnt:	0		0		0		0

alloc:
fast:		136491361	148615710	146969587	150322859
slow:		     1772	     1799	      144	      105
slow_high_order:	0		0		0		0
empty:		     1772	     1799	      144	      105
refill:		  2165245	   156302	  2332880	     2128
waive:			0		0		0		0

Jakub Kicinski (3):
  net: skb: plumb napi state thru skb freeing paths
  page_pool: allow caching from safely localized NAPI
  bnxt: hook NAPIs to page pools

 Documentation/networking/page_pool.rst    |  1 +
 drivers/net/ethernet/broadcom/bnxt/bnxt.c |  1 +
 include/linux/netdevice.h                 |  3 ++
 include/linux/skbuff.h                    | 20 +++++++----
 include/net/page_pool.h                   |  3 +-
 net/core/dev.c                            |  3 ++
 net/core/page_pool.c                      | 15 ++++++--
 net/core/skbuff.c                         | 43 ++++++++++++-----------
 8 files changed, 59 insertions(+), 30 deletions(-)

-- 
2.39.2