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From: Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>
To: Olivier Matz <olivier.matz@6wind.com>, "dev@dpdk.org" <dev@dpdk.org>
Cc: nd <nd@arm.com>,
	Honnappa Nagarahalli <Honnappa.Nagarahalli@arm.com>,
	nd <nd@arm.com>
Subject: Re: [dpdk-dev] [PATCH] test/mcslock: remove unneeded per-lcore copy
Date: Wed, 4 Nov 2020 17:57:19 +0000
Message-ID: <DBAPR08MB5814311DD78486BFCA6EFCC098EF0@DBAPR08MB5814.eurprd08.prod.outlook.com> (raw)
In-Reply-To: <20201104170425.8882-1-olivier.matz@6wind.com>

<snip>

> 
> Each core already comes with its local storage for mcslock (in its stack),
> therefore there is no need to define an additional per-lcore mcslock.
> 
> Fixes: 32dcb9fd2a22 ("test/mcslock: add MCS queued lock unit test")
> 
> Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
> ---
>  app/test/test_mcslock.c | 16 ++++++----------
>  1 file changed, 6 insertions(+), 10 deletions(-)
> 
> diff --git a/app/test/test_mcslock.c b/app/test/test_mcslock.c index
> fbca78707d..80eaecc90a 100644
> --- a/app/test/test_mcslock.c
> +++ b/app/test/test_mcslock.c
> @@ -37,10 +37,6 @@
>   *   lock multiple times.
>   */
> 
> -RTE_DEFINE_PER_LCORE(rte_mcslock_t, _ml_me); -
> RTE_DEFINE_PER_LCORE(rte_mcslock_t, _ml_try_me); -
> RTE_DEFINE_PER_LCORE(rte_mcslock_t, _ml_perf_me);
> -
>  rte_mcslock_t *p_ml;
>  rte_mcslock_t *p_ml_try;
>  rte_mcslock_t *p_ml_perf;
> @@ -53,7 +49,7 @@ static int
>  test_mcslock_per_core(__rte_unused void *arg)  {
>  	/* Per core me node. */
> -	rte_mcslock_t ml_me = RTE_PER_LCORE(_ml_me);
> +	rte_mcslock_t ml_me;
These variables are modified by other threads. IMO, it is better to keep them global (and not on the stack). From that perspective, I think we should be taking the address of the per lcore variable. For ex:
rte_mcslock_t *ml_me = &RTE_PER_LCORE(_ml_me);

> 
>  	rte_mcslock_lock(&p_ml, &ml_me);
>  	printf("MCS lock taken on core %u\n", rte_lcore_id()); @@ -77,7
> +73,7 @@ load_loop_fn(void *func_param)
>  	const unsigned int lcore = rte_lcore_id();
> 
>  	/**< Per core me node. */
> -	rte_mcslock_t ml_perf_me = RTE_PER_LCORE(_ml_perf_me);
> +	rte_mcslock_t ml_perf_me;
> 
>  	/* wait synchro */
>  	while (rte_atomic32_read(&synchro) == 0) @@ -151,8 +147,8 @@
> static int  test_mcslock_try(__rte_unused void *arg)  {
>  	/**< Per core me node. */
> -	rte_mcslock_t ml_me     = RTE_PER_LCORE(_ml_me);
> -	rte_mcslock_t ml_try_me = RTE_PER_LCORE(_ml_try_me);
> +	rte_mcslock_t ml_me;
> +	rte_mcslock_t ml_try_me;
> 
>  	/* Locked ml_try in the main lcore, so it should fail
>  	 * when trying to lock it in the worker lcore.
> @@ -178,8 +174,8 @@ test_mcslock(void)
>  	int i;
> 
>  	/* Define per core me node. */
> -	rte_mcslock_t ml_me     = RTE_PER_LCORE(_ml_me);
> -	rte_mcslock_t ml_try_me = RTE_PER_LCORE(_ml_try_me);
> +	rte_mcslock_t ml_me;
> +	rte_mcslock_t ml_try_me;
> 
>  	/*
>  	 * Test mcs lock & unlock on each core
> --
> 2.25.1


  reply	other threads:[~2020-11-04 17:57 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-04 17:04 Olivier Matz
2020-11-04 17:57 ` Honnappa Nagarahalli [this message]
2020-11-04 21:03   ` Olivier Matz
2020-11-04 21:20     ` Honnappa Nagarahalli
2021-01-15 15:28 ` David Marchand

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