[dpdk-dev] [PATCH v4 08/17] eal: apply affinity of EAL thread by assigned cpuset
Olivier MATZ
olivier.matz at 6wind.com
Sun Feb 8 21:00:41 CET 2015
Hi,
On 02/02/2015 03:02 AM, Cunming Liang wrote:
> EAL threads use assigned cpuset to set core affinity during startup.
> It keeps 1:1 mapping, if no '--lcores' option is used.
>
> [...]
>
> lib/librte_eal/bsdapp/eal/eal.c | 13 ++++---
> lib/librte_eal/bsdapp/eal/eal_thread.c | 63 +++++++++---------------------
> lib/librte_eal/linuxapp/eal/eal.c | 7 +++-
> lib/librte_eal/linuxapp/eal/eal_thread.c | 67 +++++++++++---------------------
> 4 files changed, 54 insertions(+), 96 deletions(-)
>
> diff --git a/lib/librte_eal/bsdapp/eal/eal.c b/lib/librte_eal/bsdapp/eal/eal.c
> index 69f3c03..98c5a83 100644
> --- a/lib/librte_eal/bsdapp/eal/eal.c
> +++ b/lib/librte_eal/bsdapp/eal/eal.c
> @@ -432,6 +432,7 @@ rte_eal_init(int argc, char **argv)
> int i, fctret, ret;
> pthread_t thread_id;
> static rte_atomic32_t run_once = RTE_ATOMIC32_INIT(0);
> + char cpuset[CPU_STR_LEN];
>
> if (!rte_atomic32_test_and_set(&run_once))
> return -1;
> @@ -502,13 +503,17 @@ rte_eal_init(int argc, char **argv)
> if (rte_eal_pci_init() < 0)
> rte_panic("Cannot init PCI\n");
>
> - RTE_LOG(DEBUG, EAL, "Master core %u is ready (tid=%p)\n",
> - rte_config.master_lcore, thread_id);
> -
> eal_check_mem_on_local_socket();
>
> rte_eal_mcfg_complete();
>
> + eal_thread_init_master(rte_config.master_lcore);
> +
> + eal_thread_dump_affinity(cpuset, CPU_STR_LEN);
> +
> + RTE_LOG(DEBUG, EAL, "Master lcore %u is ready (tid=%p;cpuset=[%s])\n",
> + rte_config.master_lcore, thread_id, cpuset);
> +
> if (rte_eal_dev_init() < 0)
> rte_panic("Cannot init pmd devices\n");
>
> @@ -532,8 +537,6 @@ rte_eal_init(int argc, char **argv)
> rte_panic("Cannot create thread\n");
> }
>
> - eal_thread_init_master(rte_config.master_lcore);
> -
> /*
> * Launch a dummy function on all slave lcores, so that master lcore
> * knows they are all ready when this function returns.
I wonder if changing this may have an impact on third-party drivers
that already use a management thread. Before the patch, the init()
function of the external library was called with default affinities,
and now it's called with the affinity from master lcore.
I think it should at least be noticed in the commit log.
Why are you doing this change? (I don't say it's a bad change, but
I don't understand why you are doing it here)
> diff --git a/lib/librte_eal/bsdapp/eal/eal_thread.c b/lib/librte_eal/bsdapp/eal/eal_thread.c
> index d0c077b..5b16302 100644
> --- a/lib/librte_eal/bsdapp/eal/eal_thread.c
> +++ b/lib/librte_eal/bsdapp/eal/eal_thread.c
> @@ -103,55 +103,27 @@ eal_thread_set_affinity(void)
> {
> int s;
> pthread_t thread;
> -
> -/*
> - * According to the section VERSIONS of the CPU_ALLOC man page:
> - *
> - * The CPU_ZERO(), CPU_SET(), CPU_CLR(), and CPU_ISSET() macros were added
> - * in glibc 2.3.3.
> - *
> - * CPU_COUNT() first appeared in glibc 2.6.
> - *
> - * CPU_AND(), CPU_OR(), CPU_XOR(), CPU_EQUAL(), CPU_ALLOC(),
> - * CPU_ALLOC_SIZE(), CPU_FREE(), CPU_ZERO_S(), CPU_SET_S(), CPU_CLR_S(),
> - * CPU_ISSET_S(), CPU_AND_S(), CPU_OR_S(), CPU_XOR_S(), and CPU_EQUAL_S()
> - * first appeared in glibc 2.7.
> - */
> -#if defined(CPU_ALLOC)
> - size_t size;
> - cpu_set_t *cpusetp;
> -
> - cpusetp = CPU_ALLOC(RTE_MAX_LCORE);
> - if (cpusetp == NULL) {
> - RTE_LOG(ERR, EAL, "CPU_ALLOC failed\n");
> - return -1;
> - }
> -
> - size = CPU_ALLOC_SIZE(RTE_MAX_LCORE);
> - CPU_ZERO_S(size, cpusetp);
> - CPU_SET_S(rte_lcore_id(), size, cpusetp);
> + unsigned lcore_id = rte_lcore_id();
>
> thread = pthread_self();
> - s = pthread_setaffinity_np(thread, size, cpusetp);
> + s = pthread_setaffinity_np(thread, sizeof(cpuset_t),
> + &lcore_config[lcore_id].cpuset);
> if (s != 0) {
> RTE_LOG(ERR, EAL, "pthread_setaffinity_np failed\n");
> - CPU_FREE(cpusetp);
> return -1;
> }
>
> - CPU_FREE(cpusetp);
> -#else /* CPU_ALLOC */
> - cpuset_t cpuset;
> - CPU_ZERO( &cpuset );
> - CPU_SET( rte_lcore_id(), &cpuset );
> + /* acquire system unique id */
> + rte_gettid();
As suggested in the previous patch, I think having rte_init_tid() would
be clearer here.
> +
> + /* store socket_id in TLS for quick access */
> + RTE_PER_LCORE(_socket_id) =
> + eal_cpuset_socket_id(&lcore_config[lcore_id].cpuset);
> +
> + CPU_COPY(&lcore_config[lcore_id].cpuset, &RTE_PER_LCORE(_cpuset));
> +
> + lcore_config[lcore_id].socket_id = RTE_PER_LCORE(_socket_id);
>
> - thread = pthread_self();
> - s = pthread_setaffinity_np(thread, sizeof( cpuset ), &cpuset);
> - if (s != 0) {
> - RTE_LOG(ERR, EAL, "pthread_setaffinity_np failed\n");
> - return -1;
> - }
> -#endif
You are removing a lot of code that was using CPU_ALLOC().
Are we sure that the cpuset_t type is large enough to store all the
CPUs?
It looks the current value of CPU_SETSIZE is 1024 now, but I wonder
if this code was written when this value was lower. Could you check if
it can happen today (maybe with an old libc)? A problem can occur if
the size of cpuset_t is lower that the size of RTE_MAX_LCORE.
Regards,
Olivier
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