netdev - Re: [PATCH net-next 3/3] bpf: Only set node->ref = 1 if it has not been set

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Message-ID: <376e7393-143b-aca6-4cb5-0d8987bbe8b3@fb.com>
Date:   Fri, 1 Sep 2017 07:22:52 -0700
From:   Alexei Starovoitov <ast@...com>
To:     Martin KaFai Lau <kafai@...com>, <netdev@...r.kernel.org>
CC:     Daniel Borkmann <daniel@...earbox.net>, <kernel-team@...com>
Subject: Re: [PATCH net-next 3/3] bpf: Only set node->ref = 1 if it has not
 been set

On 8/31/17 11:27 PM, Martin KaFai Lau wrote:
> This patch writes 'node->ref = 1' only if node->ref is 0.
> The number of lookups/s for a ~1M entries LRU map increased by
> ~30% (260097 to 343313).
>
> Other writes on 'node->ref = 0' is not changed.  In those cases, the
> same cache line has to be changed anyway.
>
> First column: Size of the LRU hash
> Second column: Number of lookups/s
>
> Before:
>> echo "$((2**20+1)): $(./map_perf_test 1024 1 $((2**20+1)) 10000000 | awk '{print $3}')"
> 1048577: 260097
>
> After:
>> echo "$((2**20+1)): $(./map_perf_test 1024 1 $((2**20+1)) 10000000 | awk '{print $3}')"
> 1048577: 343313
>
> Signed-off-by: Martin KaFai Lau <kafai@...com>

Acked-by: Alexei Starovoitov <ast@...nel.org>