mirrors/linux-stable
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git synced 2024-09-27 04:47:05 +00:00
Code Issues Releases Wiki Activity

SUNRPC: add list of idle threads

Browse source 
Rather than searching a list of threads to find an idle one, having a
list of idle threads allows an idle thread to be found immediately.

This adds some spin_lock calls which is not ideal, but as the hold-time
is tiny it is still faster than searching a list.  A future patch will
remove them using llist.h.  This involves some subtlety and so is left
to a separate patch.

This removes the need for the RQ_BUSY flag.  The rqst is "busy"
precisely when it is not on the "idle" list.

Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
This commit is contained in:
NeilBrown 2023-09-11 10:39:11 -04:00 committed by Chuck Lever
parent fa341560ca
commit 5ff817b235
4 changed files with 44 additions and 11 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

25
include/linux/sunrpc/svc.h
View file

@ -37,6 +37,7 @@ struct svc_pool {
struct list_head sp_sockets; /* pending sockets */
unsigned int sp_nrthreads; /* # of threads in pool */
struct list_head sp_all_threads; /* all server threads */
struct list_head sp_idle_threads; /* idle server threads */
/* statistics on pool operation */
struct percpu_counter sp_messages_arrived;
@ -186,6 +187,7 @@ extern u32 svc_max_payload(const struct svc_rqst *rqstp);
*/
struct svc_rqst {
struct list_head rq_all; /* all threads list */
struct list_head rq_idle; /* On the idle list */
struct rcu_head rq_rcu_head; /* for RCU deferred kfree */
struct svc_xprt * rq_xprt; /* transport ptr */
@ -262,10 +264,31 @@ enum {
RQ_SPLICE_OK, /* turned off in gss privacy to prevent
* encrypting page cache pages */
RQ_VICTIM, /* Have agreed to shut down */
RQ_BUSY, /* request is busy */
RQ_DATA, /* request has data */
};
/**
* svc_thread_set_busy - mark a thread as busy
* @rqstp: the thread which is now busy
*
* If rq_idle is "empty", the thread must be busy.
*/
static inline void svc_thread_set_busy(struct svc_rqst *rqstp)
{
INIT_LIST_HEAD(&rqstp->rq_idle);
}
/**
* svc_thread_busy - check if a thread as busy
* @rqstp: the thread which might be busy
*
* If rq_idle is "empty", the thread must be busy.
*/
static inline bool svc_thread_busy(struct svc_rqst *rqstp)
{
return list_empty(&rqstp->rq_idle);
}
#define SVC_NET(rqst) (rqst->rq_xprt ? rqst->rq_xprt->xpt_net : rqst->rq_bc_net)
/*

1
include/trace/events/sunrpc.h
View file

@ -1677,7 +1677,6 @@ DEFINE_SVCXDRBUF_EVENT(sendto);
svc_rqst_flag(DROPME) \
svc_rqst_flag(SPLICE_OK) \
svc_rqst_flag(VICTIM) \
svc_rqst_flag(BUSY) \
svc_rqst_flag_end(DATA)
#undef svc_rqst_flag

14
net/sunrpc/svc.c
View file

@ -510,6 +510,7 @@ __svc_create(struct svc_program *prog, unsigned int bufsize, int npools,
pool->sp_id = i;
INIT_LIST_HEAD(&pool->sp_sockets);
INIT_LIST_HEAD(&pool->sp_all_threads);
INIT_LIST_HEAD(&pool->sp_idle_threads);
spin_lock_init(&pool->sp_lock);
percpu_counter_init(&pool->sp_messages_arrived, 0, GFP_KERNEL);
@ -641,7 +642,7 @@ svc_rqst_alloc(struct svc_serv *serv, struct svc_pool *pool, int node)
folio_batch_init(&rqstp->rq_fbatch);
__set_bit(RQ_BUSY, &rqstp->rq_flags);
svc_thread_set_busy(rqstp);
rqstp->rq_server = serv;
rqstp->rq_pool = pool;
@ -702,10 +703,13 @@ void svc_pool_wake_idle_thread(struct svc_pool *pool)
struct svc_rqst *rqstp;
rcu_read_lock();
list_for_each_entry_rcu(rqstp, &pool->sp_all_threads, rq_all) {
if (test_and_set_bit(RQ_BUSY, &rqstp->rq_flags))
continue;
spin_lock_bh(&pool->sp_lock);
rqstp = list_first_entry_or_null(&pool->sp_idle_threads,
struct svc_rqst, rq_idle);
if (rqstp)
list_del_init(&rqstp->rq_idle);
spin_unlock_bh(&pool->sp_lock);
if (rqstp) {
WRITE_ONCE(rqstp->rq_qtime, ktime_get());
wake_up_process(rqstp->rq_task);
rcu_read_unlock();

15
net/sunrpc/svc_xprt.c
View file

@ -737,8 +737,9 @@ static void svc_rqst_wait_for_work(struct svc_rqst *rqstp)
set_current_state(TASK_IDLE);
smp_mb__before_atomic();
clear_bit(SP_CONGESTED, &pool->sp_flags);
clear_bit(RQ_BUSY, &rqstp->rq_flags);
smp_mb__after_atomic();
spin_lock_bh(&pool->sp_lock);
list_add(&rqstp->rq_idle, &pool->sp_idle_threads);
spin_unlock_bh(&pool->sp_lock);
/* Need to check should_sleep() again after
* setting task state in case a wakeup happened
@ -751,8 +752,14 @@ static void svc_rqst_wait_for_work(struct svc_rqst *rqstp)
cond_resched();
}
set_bit(RQ_BUSY, &rqstp->rq_flags);
smp_mb__after_atomic();
/* We *must* be removed from the list before we can continue.
* If we were woken, this is already done
*/
if (!svc_thread_busy(rqstp)) {
spin_lock_bh(&pool->sp_lock);
list_del_init(&rqstp->rq_idle);
spin_unlock_bh(&pool->sp_lock);
}
} else {
cond_resched();
}