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From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: "Ilias Apalodimas" <ilias.apalodimas@linaro.org>,
	netdev@vger.kernel.org, "Eric Dumazet" <eric.dumazet@gmail.com>,
	linux-mm@kvack.org, "Mel Gorman" <mgorman@techsingularity.net>,
	lorenzo@kernel.org, "Toke Høiland-Jørgensen" <toke@redhat.com>,
	linyunsheng@huawei.com, bpf@vger.kernel.org,
	"David S. Miller" <davem@davemloft.net>,
	"Jakub Kicinski" <kuba@kernel.org>,
	"Paolo Abeni" <pabeni@redhat.com>,
	"Andrew Morton" <akpm@linux-foundation.org>,
	willy@infradead.org
Subject: Re: [PATCH RFC net-next/mm V1 2/3] page_pool: Use static_key for shutdown phase
Date: Tue, 25 Apr 2023 16:30:27 -0700	[thread overview]
Message-ID: <20230425233027.w3olphld4nkcdvry@dhcp-172-26-102-232.dhcp.thefacebook.com> (raw)
In-Reply-To: <168244294384.1741095.6037010854411310099.stgit@firesoul>

On Tue, Apr 25, 2023 at 07:15:43PM +0200, Jesper Dangaard Brouer wrote:
> Performance is very important for page pool (PP). This add the use of
> static_key APIs for regaining a single instruction, which makes the
> new PP shutdown scheme zero impact.
> 
> We are uncertain if this is 100% correct, because static_key APIs uses
> a mutex lock and it is uncertain if all contexts that can return pages
> can support this. We could spawn a workqueue (like we just removed) to
> workaround this issue.

With debug atomic sleep the issue should be trivial to see.
iirc the callers of xdp_flush_frame_bulk() need to do it under rcu_read_lock equivalent,
which is not sleepable and mutex-es should warn.


  reply	other threads:[~2023-04-25 23:30 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-04-25 17:15 [PATCH RFC net-next/mm V1 0/3] page_pool: new approach for leak detection and " Jesper Dangaard Brouer
2023-04-25 17:15 ` [PATCH RFC net-next/mm V1 1/3] page_pool: Remove workqueue in new shutdown scheme Jesper Dangaard Brouer
2023-04-27  0:57   ` Yunsheng Lin
2023-04-27 10:47     ` Jesper Dangaard Brouer
2023-04-27 18:29       ` Jesper Dangaard Brouer
2023-04-25 17:15 ` [PATCH RFC net-next/mm V1 2/3] page_pool: Use static_key for shutdown phase Jesper Dangaard Brouer
2023-04-25 23:30   ` Alexei Starovoitov [this message]
2023-04-26 15:15     ` Jesper Dangaard Brouer
2023-04-25 17:15 ` [PATCH RFC net-next/mm V1 3/3] mm/page_pool: catch page_pool memory leaks Jesper Dangaard Brouer

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