DPDK patches and discussions
 help / color / mirror / Atom feed
From: Olivier Matz <olivier.matz@6wind.com>
To: "Hunt, David" <david.hunt@intel.com>, dev@dpdk.org
Subject: Re: [dpdk-dev] [PATCH v2 1/3] mempool: add stack (lifo) mempool handler
Date: Mon, 20 Jun 2016 10:17:36 +0200	[thread overview]
Message-ID: <5767A6A0.8000800@6wind.com> (raw)
In-Reply-To: <576406B2.5060605@intel.com>

Hi David,

On 06/17/2016 04:18 PM, Hunt, David wrote:
>> After reading it, I realize that it's nearly exactly the same code than
>> in "app/test: test external mempool handler".
>> http://patchwork.dpdk.org/dev/patchwork/patch/12896/
>>
>> We should drop one of them. If this stack handler is really useful for
>> a performance use-case, it could go in librte_mempool. At the first
>> read, the code looks like a demo example : it uses a simple spinlock for
>> concurrent accesses to the common pool. Maybe the mempool cache hides
>> this cost, in this case we could also consider removing the use of the
>> rte_ring.
> 
> While I agree that the code is similar, the handler in the test is a
> ring based handler,
> where as this patch adds an array based handler.

Not sure I'm getting what you are saying. Do you mean stack instead
of array?

Actually, both are stacks when talking about bulks of objects. If we
consider each objects one by one, that's true the order will differ.
But as discussed in [1], the cache code already reverses the order of
objects when doing a mempool_get(). I'd say the reversing in cache code
is not really needed (only the order of object bulks should remain the
same). A rte_memcpy() looks to be faster, but it would require to do
some real-life tests to validate or unvalidate this theory.

So to conclude, I still think both code in app/test and lib/mempool are
quite similar, and only one of them should be kept.

[1] http://www.dpdk.org/ml/archives/dev/2016-May/039873.html

> I think that the case for leaving it in as a test for the standard
> handler as part of the
> previous mempool handler is valid, but maybe there is a case for
> removing it if
> we add the stack handler. Maybe a future patch?
> 
>> Do you have some some performance numbers? Do you know if it scales
>> with the number of cores?
> 
> For the mempool_perf_autotest, I'm seeing a 30% increase in performance
> for the
> local cache use-case for 1 - 36 cores (results vary within those tests
> between
> 10-45% gain, but with an average of 30% gain over all the tests.).
> 
> However, for the tests with no local cache configured, throughput of the
> enqueue/dequeue
> drops by about 30%, with the 36 core yelding the largest drop of 40%. So
> this handler would
> not be recommended in no-cache applications.

Interesting, thanks. If you also have real-life (I mean network)
performance tests, I'd be interested too.

Ideally, we should have a documentation explaining in which cases a
handler or another should be used. However, if we don't know this
today, I'm not opposed to add this new handler in 16.07, and let people
do their tests and comment, then describe it properly for 16.11.

What do you think?


Regards,
Olivier

  reply	other threads:[~2016-06-20  8:17 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-05-05 18:29 [dpdk-dev] [PATCH 0/2] mempool: add stack (fifo) " David Hunt
2016-05-05 18:29 ` [dpdk-dev] [PATCH 1/2] " David Hunt
2016-05-05 21:28   ` Stephen Hemminger
2016-05-19 15:21     ` Hunt, David
2016-05-05 18:29 ` [dpdk-dev] [PATCH 2/2] test: add autotest for external mempool stack handler David Hunt
2016-05-06  8:34 ` [dpdk-dev] [PATCH 0/2] mempool: add stack (fifo) mempool handler Tan, Jianfeng
2016-05-06 23:02   ` Hunt, David
2016-05-19 14:48 ` [dpdk-dev] v2 mempool: add stack (lifo) " David Hunt
2016-05-19 14:48   ` [dpdk-dev] [PATCH v2 1/3] " David Hunt
2016-05-23 12:55     ` Olivier Matz
2016-06-15 10:10       ` Hunt, David
2016-06-17 14:18       ` Hunt, David
2016-06-20  8:17         ` Olivier Matz [this message]
2016-06-20 12:59           ` Hunt, David
2016-06-29 14:31             ` Olivier MATZ
2016-05-19 14:48   ` [dpdk-dev] [PATCH v2 2/3] mempool: make declaration of handler structs const David Hunt
2016-05-23 12:55     ` Olivier Matz
2016-05-24 14:01       ` Hunt, David
2016-05-19 14:48   ` [dpdk-dev] [PATCH v2 3/3] test: add autotest for external mempool stack handler David Hunt
2016-05-19 15:16   ` [dpdk-dev] v2 mempool: add stack (lifo) mempool handler Hunt, David
2016-06-20 13:08   ` [dpdk-dev] mempool: add stack " David Hunt
2016-06-20 13:08     ` [dpdk-dev] [PATCH v3 1/2] mempool: add stack (lifo) " David Hunt
2016-06-20 13:25       ` Jerin Jacob
2016-06-20 13:54         ` Thomas Monjalon
2016-06-20 13:58           ` Ananyev, Konstantin
2016-06-20 14:22             ` Jerin Jacob
2016-06-20 17:56               ` Ananyev, Konstantin
2016-06-21  3:35                 ` Jerin Jacob
2016-06-21  9:28                   ` Ananyev, Konstantin
2016-06-21  9:44                     ` Olivier Matz
2016-06-21  3:42           ` Jerin Jacob
2016-06-20 13:08     ` [dpdk-dev] [PATCH v3 2/2] test: add autotest for external mempool stack handler David Hunt
2016-06-30  7:41     ` [dpdk-dev] [PATCH v4 0/2] mempool: add stack mempool handler David Hunt
2016-06-30  7:41       ` [dpdk-dev] [PATCH v4 1/2] mempool: add stack (lifo) " David Hunt
2016-06-30  7:41       ` [dpdk-dev] [PATCH v4 2/2] test: migrate custom handler test to stack handler David Hunt
2016-06-30  9:45         ` Thomas Monjalon
2016-06-30 17:36           ` Hunt, David
2016-06-30 17:46             ` Thomas Monjalon
2016-06-30 17:49               ` Hunt, David
2016-06-30 18:05       ` [dpdk-dev] [PATCH v5 0/2] mempool: add stack mempool handler David Hunt
2016-06-30 18:05         ` [dpdk-dev] [PATCH v5 1/2] mempool: add stack (lifo) " David Hunt
2016-06-30 18:05         ` [dpdk-dev] [PATCH v5 2/2] test: migrate custom handler test to stack handler David Hunt
2016-07-01  7:32           ` Olivier MATZ
2016-07-01  7:46         ` [dpdk-dev] [PATCH v6 0/2] mempool: add stack mempool handler David Hunt
2016-07-01  7:46           ` [dpdk-dev] [PATCH v6 1/2] mempool: add stack (lifo) " David Hunt
2016-07-01  7:46           ` [dpdk-dev] [PATCH v6 2/2] test: migrate custom handler test to stack handler David Hunt
2016-07-01  8:18           ` [dpdk-dev] [PATCH v6 0/2] mempool: add stack mempool handler Olivier MATZ
2016-07-01 10:41             ` Thomas Monjalon

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=5767A6A0.8000800@6wind.com \
    --to=olivier.matz@6wind.com \
    --cc=david.hunt@intel.com \
    --cc=dev@dpdk.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).