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Message-ID: <45DCA0E5-F003-416C-9CA8-3C9CC7B06CDE@intel.com>
Date: Thu, 8 Mar 2018 19:22:08 +0000
From: "Dilger, Andreas" <andreas.dilger@...el.com>
To: NeilBrown <neilb@...e.com>
CC: "Drokin, Oleg" <oleg.drokin@...el.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
James Simmons <jsimmons@...radead.org>,
"Linux Kernel Mailing List" <linux-kernel@...r.kernel.org>,
Lustre Development List <lustre-devel@...ts.lustre.org>
Subject: Re: [PATCH 09/17] staging: lustre: ldlm: use delayed_work for
pools_recalc
On Mar 1, 2018, at 16:31, NeilBrown <neilb@...e.com> wrote:
>
> ldlm currenty has a kthread which wakes up every so often
> and calls ldlm_pools_recalc().
> The thread is started and stopped, but no other external interactions
> happen.
>
> This can trivially be replaced by a delayed_work if we have
> ldlm_pools_recalc() reschedule the work rather than just report
> when to do that.
>
> Signed-off-by: NeilBrown <neilb@...e.com>
Reviewed-by: Andreas Dilger <andreas.dilger@...el.com>
> ---
> drivers/staging/lustre/lustre/ldlm/ldlm_pool.c | 99 +++---------------------
> 1 file changed, 11 insertions(+), 88 deletions(-)
>
> diff --git a/drivers/staging/lustre/lustre/ldlm/ldlm_pool.c b/drivers/staging/lustre/lustre/ldlm/ldlm_pool.c
> index a0e486b57e08..53b8f33e54b5 100644
> --- a/drivers/staging/lustre/lustre/ldlm/ldlm_pool.c
> +++ b/drivers/staging/lustre/lustre/ldlm/ldlm_pool.c
> @@ -784,9 +784,6 @@ static int ldlm_pool_granted(struct ldlm_pool *pl)
> return atomic_read(&pl->pl_granted);
> }
>
> -static struct ptlrpc_thread *ldlm_pools_thread;
> -static struct completion ldlm_pools_comp;
> -
> /*
> * count locks from all namespaces (if possible). Returns number of
> * cached locks.
> @@ -899,8 +896,12 @@ static unsigned long ldlm_pools_cli_scan(struct shrinker *s,
> sc->gfp_mask);
> }
>
> -static int ldlm_pools_recalc(enum ldlm_side client)
> +static void ldlm_pools_recalc(struct work_struct *ws);
> +static DECLARE_DELAYED_WORK(ldlm_recalc_pools, ldlm_pools_recalc);
> +
> +static void ldlm_pools_recalc(struct work_struct *ws)
> {
> + enum ldlm_side client = LDLM_NAMESPACE_CLIENT;
> struct ldlm_namespace *ns;
> struct ldlm_namespace *ns_old = NULL;
> /* seconds of sleep if no active namespaces */
> @@ -982,92 +983,19 @@ static int ldlm_pools_recalc(enum ldlm_side client)
> /* Wake up the blocking threads from time to time. */
> ldlm_bl_thread_wakeup();
>
> - return time;
> -}
> -
> -static int ldlm_pools_thread_main(void *arg)
> -{
> - struct ptlrpc_thread *thread = (struct ptlrpc_thread *)arg;
> - int c_time;
> -
> - thread_set_flags(thread, SVC_RUNNING);
> - wake_up(&thread->t_ctl_waitq);
> -
> - CDEBUG(D_DLMTRACE, "%s: pool thread starting, process %d\n",
> - "ldlm_poold", current_pid());
> -
> - while (1) {
> - /*
> - * Recal all pools on this tick.
> - */
> - c_time = ldlm_pools_recalc(LDLM_NAMESPACE_CLIENT);
> -
> - /*
> - * Wait until the next check time, or until we're
> - * stopped.
> - */
> - wait_event_idle_timeout(thread->t_ctl_waitq,
> - thread_is_stopping(thread) ||
> - thread_is_event(thread),
> - c_time * HZ);
> -
> - if (thread_test_and_clear_flags(thread, SVC_STOPPING))
> - break;
> - thread_test_and_clear_flags(thread, SVC_EVENT);
> - }
> -
> - thread_set_flags(thread, SVC_STOPPED);
> - wake_up(&thread->t_ctl_waitq);
> -
> - CDEBUG(D_DLMTRACE, "%s: pool thread exiting, process %d\n",
> - "ldlm_poold", current_pid());
> -
> - complete_and_exit(&ldlm_pools_comp, 0);
> + schedule_delayed_work(&ldlm_recalc_pools, time * HZ);
> }
>
> static int ldlm_pools_thread_start(void)
> {
> - struct task_struct *task;
> -
> - if (ldlm_pools_thread)
> - return -EALREADY;
> -
> - ldlm_pools_thread = kzalloc(sizeof(*ldlm_pools_thread), GFP_NOFS);
> - if (!ldlm_pools_thread)
> - return -ENOMEM;
> -
> - init_completion(&ldlm_pools_comp);
> - init_waitqueue_head(&ldlm_pools_thread->t_ctl_waitq);
> + schedule_delayed_work(&ldlm_recalc_pools, 0);
>
> - task = kthread_run(ldlm_pools_thread_main, ldlm_pools_thread,
> - "ldlm_poold");
> - if (IS_ERR(task)) {
> - CERROR("Can't start pool thread, error %ld\n", PTR_ERR(task));
> - kfree(ldlm_pools_thread);
> - ldlm_pools_thread = NULL;
> - return PTR_ERR(task);
> - }
> - wait_event_idle(ldlm_pools_thread->t_ctl_waitq,
> - thread_is_running(ldlm_pools_thread));
> return 0;
> }
>
> static void ldlm_pools_thread_stop(void)
> {
> - if (!ldlm_pools_thread)
> - return;
> -
> - thread_set_flags(ldlm_pools_thread, SVC_STOPPING);
> - wake_up(&ldlm_pools_thread->t_ctl_waitq);
> -
> - /*
> - * Make sure that pools thread is finished before freeing @thread.
> - * This fixes possible race and oops due to accessing freed memory
> - * in pools thread.
> - */
> - wait_for_completion(&ldlm_pools_comp);
> - kfree(ldlm_pools_thread);
> - ldlm_pools_thread = NULL;
> + cancel_delayed_work_sync(&ldlm_recalc_pools);
> }
>
> static struct shrinker ldlm_pools_cli_shrinker = {
> @@ -1081,20 +1009,15 @@ int ldlm_pools_init(void)
> int rc;
>
> rc = ldlm_pools_thread_start();
> - if (rc)
> - return rc;
> -
> - rc = register_shrinker(&ldlm_pools_cli_shrinker);
> - if (rc)
> - ldlm_pools_thread_stop();
> + if (!rc)
> + rc = register_shrinker(&ldlm_pools_cli_shrinker);
>
> return rc;
> }
>
> void ldlm_pools_fini(void)
> {
> - if (ldlm_pools_thread)
> - unregister_shrinker(&ldlm_pools_cli_shrinker);
> + unregister_shrinker(&ldlm_pools_cli_shrinker);
>
> ldlm_pools_thread_stop();
> }
>
>
Cheers, Andreas
--
Andreas Dilger
Lustre Principal Architect
Intel Corporation
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