From: "Ananyev, Konstantin" <konstantin.ananyev@intel.com>
To: Dharmik Thakkar <Dharmik.Thakkar@arm.com>
Cc: Olivier Matz <olivier.matz@6wind.com>,
Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>,
"dev@dpdk.org" <dev@dpdk.org>, nd <nd@arm.com>,
Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>,
"Ruifeng Wang" <Ruifeng.Wang@arm.com>
Subject: RE: [PATCH 1/1] mempool: implement index-based per core cache
Date: Thu, 13 Jan 2022 10:37:29 +0000 [thread overview]
Message-ID: <DM6PR11MB4491342E71D9FB54BA18346C9A539@DM6PR11MB4491.namprd11.prod.outlook.com> (raw)
In-Reply-To: <8F6CF7E6-BD3D-424B-A7E1-DB6E53276DFE@arm.com>
Hi Dharmik,
> >
> >> Current mempool per core cache implementation stores pointers to mbufs
> >> On 64b architectures, each pointer consumes 8B
> >> This patch replaces it with index-based implementation,
> >> where in each buffer is addressed by (pool base address + index)
> >> It reduces the amount of memory/cache required for per core cache
> >>
> >> L3Fwd performance testing reveals minor improvements in the cache
> >> performance (L1 and L2 misses reduced by 0.60%)
> >> with no change in throughput
> >
> > I feel really sceptical about that patch and the whole idea in general:
> > - From what I read above there is no real performance improvement observed.
> > (In fact on my IA boxes mempool_perf_autotest reports ~20% slowdown,
> > see below for more details).
>
> Currently, the optimizations (loop unroll and vectorization) are only implemented for ARM64.
> Similar optimizations can be implemented for x86 platforms which should close the performance gap
> and in my understanding should give better performance for a bulk size of 32.
Might be, but I still don't see the reason for such effort.
As you mentioned there is no performance improvement in 'real' apps: l3fwd, etc.
on ARM64 even with vectorized version of the code.
> > - Space utilization difference looks neglectable too.
>
> Sorry, I did not understand this point.
As I understand one of the expectations from that patch was:
reduce memory/cache required, which should improve cache utilization
(less misses, etc.).
Though I think such improvements would be neglectable and wouldn't
cause any real performance gain.
> > - The change introduces a new build time config option with a major limitation:
> > All memzones in a pool have to be within the same 4GB boundary.
> > To address it properly, extra changes will be required in init(/populate) part of the code.
>
> I agree to the above mentioned challenges and I am currently working on resolving these issues.
I still think that to justify such changes some really noticeable performance
improvement needs to be demonstrated: double-digit speedup for l3fwd/ipsec-secgw/...
Otherwise it just not worth the hassle.
> > All that will complicate mempool code, will make it more error prone
> > and harder to maintain.
> > But, as there is no real gain in return - no point to add such extra complexity at all.
> >
> > Konstantin
> >
next prev parent reply other threads:[~2022-01-13 10:37 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-09-30 17:27 [dpdk-dev] [RFC] " Dharmik Thakkar
2021-10-01 12:36 ` Jerin Jacob
2021-10-01 15:44 ` Honnappa Nagarahalli
2021-10-01 17:32 ` Jerin Jacob
2021-10-01 17:57 ` Honnappa Nagarahalli
2021-10-01 18:21 ` Jerin Jacob
2021-10-01 21:30 ` Ananyev, Konstantin
2021-10-02 0:07 ` Honnappa Nagarahalli
2021-10-02 18:51 ` Ananyev, Konstantin
2021-10-04 16:36 ` Honnappa Nagarahalli
2021-10-30 10:23 ` Morten Brørup
2021-10-31 8:14 ` Morten Brørup
2021-11-03 15:12 ` Dharmik Thakkar
2021-11-03 15:52 ` Morten Brørup
2021-11-04 4:42 ` Dharmik Thakkar
2021-11-04 8:04 ` Morten Brørup
2021-11-08 4:32 ` Honnappa Nagarahalli
2021-11-08 7:22 ` Morten Brørup
2021-11-08 15:29 ` Honnappa Nagarahalli
2021-11-08 15:39 ` Morten Brørup
2021-11-08 15:46 ` Honnappa Nagarahalli
2021-11-08 16:03 ` Morten Brørup
2021-11-08 16:47 ` Jerin Jacob
2021-12-24 22:59 ` [PATCH 0/1] " Dharmik Thakkar
2021-12-24 22:59 ` [PATCH 1/1] " Dharmik Thakkar
2022-01-11 2:26 ` Ananyev, Konstantin
2022-01-13 5:17 ` Dharmik Thakkar
2022-01-13 10:37 ` Ananyev, Konstantin [this message]
2022-01-19 15:32 ` Dharmik Thakkar
2022-01-21 11:25 ` Ananyev, Konstantin
2022-01-21 11:31 ` Ananyev, Konstantin
2022-03-24 19:51 ` Dharmik Thakkar
2021-12-25 0:16 ` [PATCH 0/1] " Morten Brørup
2022-01-07 11:15 ` Bruce Richardson
2022-01-07 11:29 ` Morten Brørup
2022-01-07 13:50 ` Bruce Richardson
2022-01-08 9:37 ` Morten Brørup
2022-01-10 6:38 ` Jerin Jacob
2022-01-13 5:31 ` Dharmik Thakkar
2023-07-06 17:43 ` Stephen Hemminger
2023-07-31 12:23 ` Thomas Monjalon
2023-07-31 12:33 ` Morten Brørup
2023-07-31 14:57 ` Dharmik Jayesh Thakkar
2022-01-13 5:36 ` [PATCH v2 " Dharmik Thakkar
2022-01-13 5:36 ` [PATCH v2 1/1] " Dharmik Thakkar
2022-01-13 10:18 ` Jerin Jacob
2022-01-20 8:21 ` Morten Brørup
2022-01-21 6:01 ` Honnappa Nagarahalli
2022-01-21 7:36 ` Morten Brørup
2022-01-24 13:05 ` Ray Kinsella
2022-01-21 9:12 ` Bruce Richardson
2022-01-23 7:13 ` Wang, Haiyue
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