From: Stephen Hemminger <stephen@networkplumber.org>
To: Cristian Dumitrescu <cristian.dumitrescu@intel.com>
Cc: dev@dpdk.org
Subject: Re: [PATCH V2 0/6] pipeline: make the hash function configurable per table
Date: Wed, 31 Aug 2022 09:23:20 -0700 [thread overview]
Message-ID: <20220831092320.64a3a42a@hermes.local> (raw)
In-Reply-To: <20220819195225.1483020-1-cristian.dumitrescu@intel.com>
On Fri, 19 Aug 2022 19:52:19 +0000
Cristian Dumitrescu <cristian.dumitrescu@intel.com> wrote:
> Also, since this flexibility has some performance cost, this patch set
> also introduces key comparison functions specialized for each key size
> value. Since the key size is fixed for each table, the key comparison
> function can be selected at initialization as opposed to using a
> generic function that can handle any key size. This strategy result in
> a performance improvement for the table lookup operation of around 5%.
I wonder if DPDK should start to adopt the Linux kernel optimizations
around indirect calls. For most all cases, the function pointer will be
a certain value and the cpu can do direct rather than indirect call.
As in:
if (likely(hash_func == crc32_hash))
crc32_hash(x, y)
else
(*hash_func)(x, y)
This was done in Linux kernel because of the overhead of the Spectre/Meltdown
mitigation's, but could apply more generally in DPDK.
next prev parent reply other threads:[~2022-08-31 16:23 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-18 11:44 [PATCH " Cristian Dumitrescu
2022-08-18 11:44 ` [PATCH 1/6] table: add hash function prototype Cristian Dumitrescu
2022-08-18 11:44 ` [PATCH 2/6] table: add key comparison functions Cristian Dumitrescu
2022-08-18 11:44 ` [PATCH 3/6] table: configure the hash function for regular tables Cristian Dumitrescu
2022-08-18 11:44 ` [PATCH 4/6] pipeline: " Cristian Dumitrescu
2022-08-18 11:44 ` [PATCH 5/6] table: configure the hash function for learner tables Cristian Dumitrescu
2022-08-18 11:44 ` [PATCH 6/6] pipeline: " Cristian Dumitrescu
2022-08-19 19:52 ` [PATCH V2 0/6] pipeline: make the hash function configurable per table Cristian Dumitrescu
2022-08-19 19:52 ` [PATCH V2 1/6] table: add hash function prototype Cristian Dumitrescu
2022-08-19 19:52 ` [PATCH V2 2/6] table: add key comparison functions Cristian Dumitrescu
2022-08-19 19:52 ` [PATCH V2 3/6] table: configure the hash function for regular tables Cristian Dumitrescu
2022-08-19 19:52 ` [PATCH V2 4/6] pipeline: " Cristian Dumitrescu
2022-08-19 19:52 ` [PATCH V2 5/6] table: configure the hash function for learner tables Cristian Dumitrescu
2022-08-19 19:52 ` [PATCH V2 6/6] pipeline: " Cristian Dumitrescu
2022-08-31 16:23 ` Stephen Hemminger [this message]
2022-09-01 8:11 ` [PATCH V2 0/6] pipeline: make the hash function configurable per table Morten Brørup
2022-09-23 15:58 ` Thomas Monjalon
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