From: "Toke Høiland-Jørgensen" <toke@redhat.com>
To: Jakub Kicinski <kuba@kernel.org>,
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, linyunsheng@huawei.com, bpf@vger.kernel.org,
"David S. Miller" <davem@davemloft.net>,
Paolo Abeni <pabeni@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
willy@infradead.org
Subject: Re: [PATCH RFC net-next/mm V3 1/2] page_pool: Remove workqueue in new shutdown scheme
Date: Wed, 03 May 2023 13:18:47 +0200 [thread overview]
Message-ID: <87ednxbr3c.fsf@toke.dk> (raw)
In-Reply-To: <20230502193309.382af41e@kernel.org>
Jakub Kicinski <kuba@kernel.org> writes:
> On Fri, 28 Apr 2023 18:16:19 +0200 Jesper Dangaard Brouer wrote:
>> This removes the workqueue scheme that periodically tests when
>> inflight reach zero such that page_pool memory can be freed.
>>
>> This change adds code to fast-path free checking for a shutdown flags
>> bit after returning PP pages.
>
> We can remove the warning without removing the entire delayed freeing
> scheme. I definitely like the SHUTDOWN flag and patch 2 but I'm a bit
> less clear on why the complexity of datapath freeing is justified.
> Can you explain?
You mean just let the workqueue keep rescheduling itself every minute
for the (potentially) hours that skbs will stick around? Seems a bit
wasteful, doesn't it? :)
We did see an issue where creating and tearing down lots of page pools
in a short period of time caused significant slowdowns due to the
workqueue mechanism. Lots being "thousands per second". This is possible
using the live packet mode of bpf_prog_run() for XDP, which will setup
and destroy a page pool for each syscall...
-Toke
next prev parent reply other threads:[~2023-05-03 11:18 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-28 16:16 [PATCH RFC net-next/mm V3 0/2] page_pool: new approach for leak detection and shutdown phase Jesper Dangaard Brouer
2023-04-28 16:16 ` [PATCH RFC net-next/mm V3 1/2] page_pool: Remove workqueue in new shutdown scheme Jesper Dangaard Brouer
2023-04-28 21:38 ` Toke Høiland-Jørgensen
2023-05-03 15:21 ` Jesper Dangaard Brouer
2023-05-03 2:33 ` Jakub Kicinski
2023-05-03 11:18 ` Toke Høiland-Jørgensen [this message]
2023-05-03 15:49 ` Jesper Dangaard Brouer
2023-05-04 1:47 ` Jakub Kicinski
2023-05-04 2:42 ` Yunsheng Lin
2023-05-04 13:48 ` Jesper Dangaard Brouer
2023-05-05 0:54 ` Yunsheng Lin
2023-05-06 13:11 ` Yunsheng Lin
2023-04-28 16:16 ` [PATCH RFC net-next/mm V3 2/2] mm/page_pool: catch page_pool memory leaks Jesper Dangaard Brouer
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