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From: Olivier Matz <olivier.matz@6wind.com>
To: Zoltan Kiss <zoltan.kiss@linaro.org>,
	Zoltan Kiss <zoltan.kiss@schaman.hu>,
	dev@dpdk.org
Cc: Bruce Richardson <bruce.richardson@intel.com>
Subject: Re: [dpdk-dev] [PATCH v2] mempool: adjust name string size in related data types
Date: Thu, 21 Jul 2016 16:25:41 +0200	[thread overview]
Message-ID: <1e8aa5d1-b83e-5e35-e382-b0cc685ffb56@6wind.com> (raw)
In-Reply-To: <34eb5f3b-307a-3072-d262-e46a6437eea7@linaro.org>



On 07/21/2016 03:47 PM, Zoltan Kiss wrote:
> 
> 
> On 21/07/16 14:40, Olivier Matz wrote:
>> Hi Zoltan,
>>
>>
>> On 07/20/2016 07:16 PM, Zoltan Kiss wrote:
>>> A recent patch brought up an issue about the size of the 'name' fields:
>>>
>>> 85cf0079 mem: avoid memzone/mempool/ring name truncation
>>>
>>> These relations should be observed:
>>>
>>> 1. Each ring creates a memzone with a prefixed name:
>>> RTE_RING_NAMESIZE <= RTE_MEMZONE_NAMESIZE - strlen(RTE_RING_MZ_PREFIX)
>>>
>>> 2. There are some mempool handlers which create a ring with a prefixed
>>> name:
>>> RTE_MEMPOOL_NAMESIZE <= RTE_RING_NAMESIZE -
>>> strlen(RTE_MEMPOOL_MZ_PREFIX)
>>>
>>> 3. A mempool can create up to RTE_MAX_MEMZONE pre and postfixed
>>> memzones:
>>> sprintf(postfix, "_%d", RTE_MAX_MEMZONE)
>>> RTE_MEMPOOL_NAMESIZE <= RTE_MEMZONE_NAMESIZE -
>>>     strlen(RTE_MEMPOOL_MZ_PREFIX) - strlen(postfix)
>>>
>>> Setting all of them to 32 hides this restriction from the application.
>>> This patch decreases the mempool and ring string size to accommodate for
>>> these prefixes, but it doesn't apply the 3rd constraint. Applications
>>> relying on these constants need to be recompiled, otherwise they'll run
>>> into ENAMETOOLONG issues.
>>> The size of the arrays are kept 32 for ABI compatibility, it can be
>>> decreased next time the ABI changes.
>>>
>>> Signed-off-by: Zoltan Kiss <zoltan.kiss@schaman.hu>
>>
>> Looks like to be a good compromise for the 16.07 release. One question
>> however: why not taking in account the 3rd constraint? Because it may
>> not completly fix the issue if the mempool is fragmented.
>>
>> We could define RTE_MEMPOOL_NAMESIZE to 24
>>  = 32 - len('mp_') - len('_0123'))
> 
> I was trying to figure out a compile time macro for strlen(postfix), but
> I could not. Your suggestion would work only until someone increases
> RTE_MAX_MEMZONE above 9999. As the likelihood of fragmenting a pool over
> 99 memzones seems small, I did not bother to fix this with an ugly hack,
> but if you think we should include it, let me know!

Ok, looks fair, thanks for the clarification.

Acked-by: Olivier Matz <olivier.matz@6wind.com>

  reply	other threads:[~2016-07-21 14:25 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-07-19 14:37 [dpdk-dev] [PATCH] mempool: fix lack of free() registration Zoltan Kiss
2016-07-19 14:37 ` [dpdk-dev] [PATCH] mempool: adjust name string size in related data types Zoltan Kiss
2016-07-19 15:37   ` Olivier Matz
2016-07-19 15:59     ` Zoltan Kiss
2016-07-19 16:17       ` Olivier Matz
2016-07-20 12:41         ` Zoltan Kiss
2016-07-20 13:37           ` Olivier Matz
2016-07-20 14:01             ` Richardson, Bruce
2016-07-20 17:20             ` Zoltan Kiss
2016-07-20 17:16   ` [dpdk-dev] [PATCH v2] " Zoltan Kiss
2016-07-21 13:40     ` Olivier Matz
2016-07-21 13:47       ` Zoltan Kiss
2016-07-21 14:25         ` Olivier Matz [this message]
2016-07-21 21:16           ` Thomas Monjalon
2016-07-19 15:26 ` [dpdk-dev] [PATCH] mempool: fix lack of free() registration Olivier Matz
2016-07-19 16:17   ` Zoltan Kiss
2016-07-20 17:14 ` [dpdk-dev] [PATCH v2] mempool: fix lack of free registration Zoltan Kiss
2016-07-21 21:04   ` Thomas Monjalon

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