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Date: Mon, 18 Dec 2023 17:09:56 +0800
From: Hangbin Liu <liuhangbin@gmail.com>
To: Dmitry Safonov <dima@arista.com>
Cc: Shuah Khan <shuah@kernel.org>, David Ahern <dsahern@kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	Eric Dumazet <edumazet@google.com>,
	Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
	Salam Noureddine <noureddine@arista.com>,
	Bob Gilligan <gilligan@arista.com>, linux-kernel@vger.kernel.org,
	linux-kselftest@vger.kernel.org, netdev@vger.kernel.org,
	Dmitry Safonov <0x7f454c46@gmail.com>
Subject: Re: [PATCH 07/12] selftests/net: Add test/benchmark for removing MKTs
Message-ID: <ZYAMZE07FfZVYHH2@Laptop-X1>
References: <20231215-tcp-ao-selftests-v1-0-f6c08180b985@arista.com>
 <20231215-tcp-ao-selftests-v1-7-f6c08180b985@arista.com>
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In-Reply-To: <20231215-tcp-ao-selftests-v1-7-f6c08180b985@arista.com>

On Fri, Dec 15, 2023 at 02:36:21AM +0000, Dmitry Safonov wrote:
> Sample output:
> > 1..36
> > # 1106[lib/setup.c:207] rand seed 1660754406
> > TAP version 13
> > ok 1   Worst case connect       512 keys: min=0ms max=1ms mean=0.583329ms stddev=0.076376
> > ok 2 Connect random-search      512 keys: min=0ms max=1ms mean=0.53412ms stddev=0.0516779
> > ok 3    Worst case delete       512 keys: min=2ms max=11ms mean=6.04139ms stddev=0.245792
> > ok 4        Add a new key       512 keys: min=0ms max=13ms mean=0.673415ms stddev=0.0820618
> > ok 5 Remove random-search       512 keys: min=5ms max=9ms mean=6.65969ms stddev=0.258064
> > ok 6         Remove async       512 keys: min=0ms max=0ms mean=0.041825ms stddev=0.0204512
> > ok 7   Worst case connect       1024 keys: min=0ms max=2ms mean=0.520357ms stddev=0.0721358
> > ok 8 Connect random-search      1024 keys: min=0ms max=2ms mean=0.535312ms stddev=0.0517355
> > ok 9    Worst case delete       1024 keys: min=5ms max=9ms mean=8.27219ms stddev=0.287614
> > ok 10        Add a new key      1024 keys: min=0ms max=1ms mean=0.688121ms stddev=0.0829531
> > ok 11 Remove random-search      1024 keys: min=5ms max=9ms mean=8.37649ms stddev=0.289422
> > ok 12         Remove async      1024 keys: min=0ms max=0ms mean=0.0457096ms stddev=0.0213798
> > ok 13   Worst case connect      2048 keys: min=0ms max=2ms mean=0.748804ms stddev=0.0865335
> > ok 14 Connect random-search     2048 keys: min=0ms max=2ms mean=0.782993ms stddev=0.0625697
> > ok 15    Worst case delete      2048 keys: min=5ms max=10ms mean=8.23106ms stddev=0.286898
> > ok 16        Add a new key      2048 keys: min=0ms max=1ms mean=0.812988ms stddev=0.0901658
> > ok 17 Remove random-search      2048 keys: min=8ms max=9ms mean=8.84949ms stddev=0.297481
> > ok 18         Remove async      2048 keys: min=0ms max=0ms mean=0.0297223ms stddev=0.0172402
> > ok 19   Worst case connect      4096 keys: min=1ms max=5ms mean=1.53352ms stddev=0.123836
> > ok 20 Connect random-search     4096 keys: min=1ms max=5ms mean=1.52226ms stddev=0.0872429
> > ok 21    Worst case delete      4096 keys: min=5ms max=9ms mean=8.25874ms stddev=0.28738
> > ok 22        Add a new key      4096 keys: min=0ms max=3ms mean=1.67382ms stddev=0.129376
> > ok 23 Remove random-search      4096 keys: min=5ms max=10ms mean=8.26178ms stddev=0.287433
> > ok 24         Remove async      4096 keys: min=0ms max=0ms mean=0.0340009ms stddev=0.0184393
> > ok 25   Worst case connect      8192 keys: min=2ms max=4ms mean=2.86208ms stddev=0.169177
> > ok 26 Connect random-search     8192 keys: min=2ms max=4ms mean=2.87592ms stddev=0.119915
> > ok 27    Worst case delete      8192 keys: min=6ms max=11ms mean=7.55291ms stddev=0.274826
> > ok 28        Add a new key      8192 keys: min=1ms max=5ms mean=2.56797ms stddev=0.160249
> > ok 29 Remove random-search      8192 keys: min=5ms max=10ms mean=7.14002ms stddev=0.267208
> > ok 30         Remove async      8192 keys: min=0ms max=0ms mean=0.0320066ms stddev=0.0178904
> > ok 31   Worst case connect      16384 keys: min=5ms max=6ms mean=5.55334ms stddev=0.235655
> > ok 32 Connect random-search     16384 keys: min=5ms max=6ms mean=5.52614ms stddev=0.166225
> > ok 33    Worst case delete      16384 keys: min=5ms max=11ms mean=7.39109ms stddev=0.271866
> > ok 34        Add a new key      16384 keys: min=2ms max=4ms mean=3.35799ms stddev=0.183248
> > ok 35 Remove random-search      16384 keys: min=5ms max=8ms mean=6.86078ms stddev=0.261931
> > ok 36         Remove async      16384 keys: min=0ms max=0ms mean=0.0302384ms stddev=0.0173892
> > # Totals: pass:36 fail:0 xfail:0 xpass:0 skip:0 error:0
> 
> From the output it's visible that the current simplified approach with
> linked-list of MKTs scales quite fine even for thousands of keys.
> And that also means that the majority of the time for delete is eaten by
> synchronize_rcu() [which I can confirm separately by tracing].
> 
> Signed-off-by: Dmitry Safonov <dima@arista.com>

Tested-by: Hangbin Liu <liuhangbin@gmail.com>