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From: Stephen Hemminger <stephen@networkplumber.org>
To: Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>
Cc: Yipeng Wang <yipeng1.wang@intel.com>,
	Sameh Gobriel <sameh.gobriel@intel.com>,
	Bruce Richardson <bruce.richardson@intel.com>,
	"dev@dpdk.org" <dev@dpdk.org>,
	"pablo.de.lara.guarch@intel.com" <pablo.de.lara.guarch@intel.com>,
	nd <nd@arm.com>
Subject: Re: [dpdk-dev] [PATCH] hash: document breakage with multi-writer thread
Date: Thu, 4 Jun 2020 10:58:17 -0700
Message-ID: <20200604105817.1a3a2749@hermes.lan> (raw)
In-Reply-To: <DB6PR0802MB221691379E0AAD8CAC76F3C398890@DB6PR0802MB2216.eurprd08.prod.outlook.com>

On Thu, 4 Jun 2020 17:51:43 +0000
Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com> wrote:

> <snip>
> 
> > Subject: [PATCH] hash: document breakage with multi-writer thread
> > 
> > The code in rte_cuckoo_hash multi-writer support is broken if write
> > operations are called from a non-EAL thread.
> > 
> > rte_lcore_id() wil return LCORE_ID_ANY (UINT32_MAX) for non EAL thread
> > and that leads to using wrong local cache.
> > 
> > Add error checks and document the restriction.  
> Having multiple non-EAL writer threads is a valid use case. Should we fix the issue instead?

Discovered this the hard way...

Fixing is non-trivial. Basically, the local cache has to be take out and
that leads to having to do real locking or atomic operations.

  reply	other threads:[~2020-06-04 17:58 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-04 17:17 Stephen Hemminger
2020-06-04 17:51 ` Honnappa Nagarahalli
2020-06-04 17:58   ` Stephen Hemminger [this message]
2020-06-04 18:43     ` Honnappa Nagarahalli
2020-06-04 19:10       ` Wang, Yipeng1
2020-06-04 19:34         ` Honnappa Nagarahalli
2020-06-04 20:22           ` Wang, Yipeng1
2020-06-04 21:06             ` Stephen Hemminger
2020-06-04 21:32 ` Wang, Yipeng1
2020-06-05 18:35 ` Stephen Hemminger
2020-06-16 16:12   ` Thomas Monjalon
2020-11-26 17:56     ` Thomas Monjalon

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