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From: "Burakov, Anatoly" <anatoly.burakov@intel.com>
To: Gage Eads <gage.eads@intel.com>, dev@dpdk.org
Cc: olivier.matz@6wind.com, arybchenko@solarflare.com,
	bruce.richardson@intel.com, konstantin.ananyev@intel.com
Subject: Re: [PATCH 1/6] ring: change head and tail to pointer-width size
Date: Fri, 11 Jan 2019 10:25:25 +0000	[thread overview]
Message-ID: <e539c282-d18c-ce71-3cda-1868c4d57ee9@intel.com> (raw)
In-Reply-To: <20190110210122.24889-2-gage.eads@intel.com>

On 10-Jan-19 9:01 PM, Gage Eads wrote:
> For 64-bit architectures, doubling the head and tail index widths greatly
> increases the time it takes for them to wrap-around (with current CPU
> speeds, it won't happen within the author's lifetime). This is important in
> avoiding the ABA problem -- in which a thread mistakes reading the same
> tail index in two accesses to mean that the ring was not modified in the
> intervening time -- in the upcoming non-blocking ring implementation. Using
> a 64-bit index makes the possibility of this occurring effectively zero.
> 
> I tested this commit's performance impact with an x86_64 build on a
> dual-socket Xeon E5-2699 v4 using ring_perf_autotest, and the change made
> no significant difference -- the few differences appear to be system noise.
> (The test ran on isolcpus cores using a tickless scheduler, but some
> variation was stll observed.) Each test was run three times and the results
> were averaged:
> 
>                                    | 64b head/tail cycle cost minus
>               Test                 |     32b head/tail cycle cost
> ------------------------------------------------------------------
> SP/SC single enq/dequeue          | 0.33
> MP/MC single enq/dequeue          | 0.00
> SP/SC burst enq/dequeue (size 8)  | 0.00
> MP/MC burst enq/dequeue (size 8)  | 1.00
> SP/SC burst enq/dequeue (size 32) | 0.00
> MP/MC burst enq/dequeue (size 32) | -1.00
> SC empty dequeue                  | 0.01
> MC empty dequeue                  | 0.00
> 
> Single lcore:
> SP/SC bulk enq/dequeue (size 8)   | -0.36
> MP/MC bulk enq/dequeue (size 8)   | 0.99
> SP/SC bulk enq/dequeue (size 32)  | -0.40
> MP/MC bulk enq/dequeue (size 32)  | -0.57
> 
> Two physical cores:
> SP/SC bulk enq/dequeue (size 8)   | -0.49
> MP/MC bulk enq/dequeue (size 8)   | 0.19
> SP/SC bulk enq/dequeue (size 32)  | -0.28
> MP/MC bulk enq/dequeue (size 32)  | -0.62
> 
> Two NUMA nodes:
> SP/SC bulk enq/dequeue (size 8)   | 3.25
> MP/MC bulk enq/dequeue (size 8)   | 1.87
> SP/SC bulk enq/dequeue (size 32)  | -0.44
> MP/MC bulk enq/dequeue (size 32)  | -1.10
> 
> An earlier version of this patch changed the head and tail indexes to
> uint64_t, but that caused a performance drop on 32-bit builds. With
> uintptr_t, no performance difference is observed on an i686 build.
> 
> Signed-off-by: Gage Eads <gage.eads@intel.com>
> ---

You're breaking the ABI - version bump for affected libraries is needed.

-- 
Thanks,
Anatoly

  parent reply	other threads:[~2019-01-11 10:25 UTC|newest]

Thread overview: 102+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-10 21:01 [PATCH 0/6] Add non-blocking ring Gage Eads
2019-01-10 21:01 ` [PATCH 1/6] ring: change head and tail to pointer-width size Gage Eads
2019-01-11  4:38   ` Stephen Hemminger
2019-01-11 19:07     ` Eads, Gage
2019-01-11 10:25   ` Burakov, Anatoly [this message]
2019-01-11 19:12     ` Eads, Gage
2019-01-11 19:55       ` Stephen Hemminger
2019-01-15 15:48         ` Eads, Gage
2019-01-11 10:40   ` Burakov, Anatoly
2019-01-11 10:58     ` Bruce Richardson
2019-01-11 11:30       ` Burakov, Anatoly
     [not found]         ` <20190111115851.GC3336@bricha3-MOBL.ger.corp.intel.com>
2019-01-11 19:27           ` Eads, Gage
2019-01-21 14:14             ` Burakov, Anatoly
2019-01-22 18:27               ` Eads, Gage
2019-01-10 21:01 ` [PATCH 2/6] ring: add a non-blocking implementation Gage Eads
2019-01-10 21:01 ` [PATCH 3/6] test_ring: add non-blocking ring autotest Gage Eads
2019-01-10 21:01 ` [PATCH 4/6] test_ring_perf: add non-blocking ring perf test Gage Eads
2019-01-10 21:01 ` [PATCH 5/6] mempool/ring: add non-blocking ring handlers Gage Eads
2019-01-13 13:43   ` Andrew Rybchenko
2019-01-10 21:01 ` [PATCH 6/6] doc: add NB ring comment to EAL "known issues" Gage Eads
2019-01-11  2:51   ` Varghese, Vipin
2019-01-11 19:30     ` Eads, Gage
2019-01-14  0:07       ` Varghese, Vipin
2019-01-15 23:52 ` [PATCH v2 0/5] Add non-blocking ring Gage Eads
2019-01-15 23:52   ` [PATCH v2 1/5] ring: change head and tail to pointer-width size Gage Eads
2019-01-15 23:52   ` [PATCH v2 2/5] ring: add a non-blocking implementation Gage Eads
2019-01-15 23:52   ` [PATCH v2 3/5] test_ring: add non-blocking ring autotest Gage Eads
2019-01-15 23:52   ` [PATCH v2 4/5] test_ring_perf: add non-blocking ring perf test Gage Eads
2019-01-15 23:52   ` [PATCH v2 5/5] mempool/ring: add non-blocking ring handlers Gage Eads
2019-01-16  0:26   ` [PATCH v2 0/5] Add non-blocking ring Stephen Hemminger
2019-01-18 15:23   ` [PATCH v3 " Gage Eads
2019-01-18 15:23     ` [PATCH v3 1/5] ring: add 64-bit headtail structure Gage Eads
2019-01-18 15:23     ` [PATCH v3 2/5] ring: add a non-blocking implementation Gage Eads
2019-01-22 10:12       ` Ola Liljedahl
2019-01-22 14:49       ` Ola Liljedahl
2019-01-22 21:31         ` Eads, Gage
2019-01-23 10:16           ` Ola Liljedahl
2019-01-25 17:21             ` Eads, Gage
2019-01-28 10:35               ` Ola Liljedahl
2019-01-28 18:54                 ` Eads, Gage
2019-01-28 22:31                   ` Ola Liljedahl
2019-01-28 13:34               ` Jerin Jacob Kollanukkaran
2019-01-28 13:43                 ` Ola Liljedahl
2019-01-28 14:04                   ` Jerin Jacob Kollanukkaran
2019-01-28 14:06                     ` Ola Liljedahl
2019-01-28 18:59                 ` Eads, Gage
2019-01-18 15:23     ` [PATCH v3 3/5] test_ring: add non-blocking ring autotest Gage Eads
2019-01-18 15:23     ` [PATCH v3 4/5] test_ring_perf: add non-blocking ring perf test Gage Eads
2019-01-18 15:23     ` [PATCH v3 5/5] mempool/ring: add non-blocking ring handlers Gage Eads
2019-01-22  9:27     ` [PATCH v3 0/5] Add non-blocking ring Ola Liljedahl
2019-01-22 10:15       ` Ola Liljedahl
2019-01-22 19:15       ` Eads, Gage
2019-01-23 16:02       ` Jerin Jacob Kollanukkaran
2019-01-23 16:29         ` Ola Liljedahl
2019-01-28 13:10           ` [EXT] " Jerin Jacob Kollanukkaran
2019-01-25  5:20     ` Honnappa Nagarahalli
2019-01-25 17:42       ` Eads, Gage
2019-01-25 17:56       ` Eads, Gage
2019-01-28 10:41         ` Ola Liljedahl
2019-01-28 18:14     ` [PATCH v4 " Gage Eads
2019-01-28 18:14       ` [PATCH v4 1/5] ring: add 64-bit headtail structure Gage Eads
2019-01-29 12:56         ` Ola Liljedahl
2019-01-30  4:26           ` Eads, Gage
2019-01-28 18:14       ` [PATCH v4 2/5] ring: add a non-blocking implementation Gage Eads
2019-01-28 18:14       ` [PATCH v4 3/5] test_ring: add non-blocking ring autotest Gage Eads
2019-01-28 18:14       ` [PATCH v4 4/5] test_ring_perf: add non-blocking ring perf test Gage Eads
2019-01-28 18:14       ` [PATCH v4 5/5] mempool/ring: add non-blocking ring handlers Gage Eads
2019-03-05 17:40       ` [PATCH v5 0/6] Add lock-free ring and mempool handler Gage Eads
2019-03-05 17:40         ` [PATCH v5 1/6] ring: add a pointer-width headtail structure Gage Eads
2019-03-05 17:40         ` [PATCH v5 2/6] ring: add a ring start marker Gage Eads
2019-03-05 17:40         ` [PATCH v5 3/6] ring: add a lock-free implementation Gage Eads
2019-03-05 17:40         ` [PATCH v5 4/6] test_ring: add lock-free ring autotest Gage Eads
2019-03-05 17:40         ` [PATCH v5 5/6] test_ring_perf: add lock-free ring perf test Gage Eads
2019-03-05 17:40         ` [PATCH v5 6/6] mempool/ring: add lock-free ring handlers Gage Eads
2019-03-06 15:03         ` [PATCH v6 0/6] Add lock-free ring and mempool handler Gage Eads
2019-03-06 15:03           ` [PATCH v6 1/6] ring: add a pointer-width headtail structure Gage Eads
2019-03-06 15:03           ` [PATCH v6 2/6] ring: add a ring start marker Gage Eads
2019-03-06 15:03           ` [PATCH v6 3/6] ring: add a lock-free implementation Gage Eads
2019-03-06 15:03           ` [PATCH v6 4/6] test_ring: add lock-free ring autotest Gage Eads
2019-03-06 15:03           ` [PATCH v6 5/6] test_ring_perf: add lock-free ring perf test Gage Eads
2019-03-06 15:03           ` [PATCH v6 6/6] mempool/ring: add lock-free ring handlers Gage Eads
2019-03-18 21:35           ` [PATCH v7 0/6] Add lock-free ring and mempool handler Gage Eads
2019-03-18 21:35             ` [PATCH v7 1/6] ring: add a pointer-width headtail structure Gage Eads
2019-03-18 21:35             ` [PATCH v7 2/6] ring: add a ring start marker Gage Eads
2019-03-18 21:35             ` [PATCH v7 3/6] ring: add a lock-free implementation Gage Eads
2019-03-19 15:50               ` Stephen Hemminger
2019-03-18 21:35             ` [PATCH v7 4/6] test_ring: add lock-free ring autotest Gage Eads
2019-03-18 21:35             ` [PATCH v7 5/6] test_ring_perf: add lock-free ring perf test Gage Eads
2019-03-18 21:35             ` [PATCH v7 6/6] mempool/ring: add lock-free ring handlers Gage Eads
2019-03-18 21:49             ` [PATCH v7 0/6] Add lock-free ring and mempool handler Eads, Gage
2019-03-19 15:51               ` Stephen Hemminger
2019-04-01 19:23                 ` Eads, Gage
2019-04-02 10:16                   ` Ola Liljedahl
2019-04-04 22:28                     ` [dpdk-dev] " Eads, Gage
2019-03-19  1:20             ` [PATCH v8 " Gage Eads
2019-03-19  1:20               ` [PATCH v8 1/6] ring: add a pointer-width headtail structure Gage Eads
2019-03-19  1:20               ` [PATCH v8 2/6] ring: add a ring start marker Gage Eads
2019-03-19  1:20               ` [PATCH v8 3/6] ring: add a lock-free implementation Gage Eads
2019-03-19  1:20               ` [PATCH v8 4/6] test_ring: add lock-free ring autotest Gage Eads
2019-03-19  1:20               ` [PATCH v8 5/6] test_ring_perf: add lock-free ring perf test Gage Eads
2019-03-19  1:20               ` [PATCH v8 6/6] mempool/ring: add lock-free ring handlers Gage Eads
2019-04-03 16:46               ` [PATCH v8 0/6] Add lock-free ring and mempool handler Thomas Monjalon

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