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SUNRPC: Remove the .svo_enqueue_xprt method

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We have never been able to track down and address the underlying
cause of the performance issues with workqueue-based service
support. svo_enqueue_xprt is called multiple times per RPC, so
it adds instruction path length, but always ends up at the same
function: svc_xprt_do_enqueue(). We do not anticipate needing
this flexibility for dynamic nfsd thread management support.

As a micro-optimization, remove .svo_enqueue_xprt because
Spectre/Meltdown makes virtual function calls more costly.

This change essentially reverts commit b9e13cdfac ("nfsd/sunrpc:
turn enqueueing a svc_xprt into a svc_serv operation").

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
This commit is contained in:
Chuck Lever 2022-01-25 10:17:59 -05:00
parent 70a60cbfb6
commit a9ff2e99e9
6 changed files with 5 additions and 13 deletions
Download patch file Download diff file Expand all files Collapse all files

1
fs/lockd/svc.c
View file

@ -353,7 +353,6 @@ static struct notifier_block lockd_inet6addr_notifier = {
static const struct svc_serv_ops lockd_sv_ops = { static const struct svc_serv_ops lockd_sv_ops = {
.svo_shutdown = svc_rpcb_cleanup, .svo_shutdown = svc_rpcb_cleanup,
.svo_function = lockd, .svo_function = lockd,
.svo_enqueue_xprt = svc_xprt_do_enqueue,
.svo_module = THIS_MODULE, .svo_module = THIS_MODULE,
}; };

2
fs/nfs/callback.c
View file

@ -234,13 +234,11 @@ err_bind:
static const struct svc_serv_ops nfs40_cb_sv_ops = { static const struct svc_serv_ops nfs40_cb_sv_ops = {
.svo_function = nfs4_callback_svc, .svo_function = nfs4_callback_svc,
.svo_enqueue_xprt = svc_xprt_do_enqueue,
.svo_module = THIS_MODULE, .svo_module = THIS_MODULE,
}; };
#if defined(CONFIG_NFS_V4_1) #if defined(CONFIG_NFS_V4_1)
static const struct svc_serv_ops nfs41_cb_sv_ops = { static const struct svc_serv_ops nfs41_cb_sv_ops = {
.svo_function = nfs41_callback_svc, .svo_function = nfs41_callback_svc,
.svo_enqueue_xprt = svc_xprt_do_enqueue,
.svo_module = THIS_MODULE, .svo_module = THIS_MODULE,
}; };

1
fs/nfsd/nfssvc.c
View file

@ -615,7 +615,6 @@ static int nfsd_get_default_max_blksize(void)
static const struct svc_serv_ops nfsd_thread_sv_ops = { static const struct svc_serv_ops nfsd_thread_sv_ops = {
.svo_shutdown = nfsd_last_thread, .svo_shutdown = nfsd_last_thread,
.svo_function = nfsd, .svo_function = nfsd,
.svo_enqueue_xprt = svc_xprt_do_enqueue,
.svo_module = THIS_MODULE, .svo_module = THIS_MODULE,
}; };

3
include/linux/sunrpc/svc.h
View file

@ -61,9 +61,6 @@ struct svc_serv_ops {
/* function for service threads to run */ /* function for service threads to run */
int (*svo_function)(void *); int (*svo_function)(void *);
/* queue up a transport for servicing */
void (*svo_enqueue_xprt)(struct svc_xprt *);
/* optional module to count when adding threads. /* optional module to count when adding threads.
* Thread function must call module_put_and_kthread_exit() to exit. * Thread function must call module_put_and_kthread_exit() to exit.
*/ */

1
include/linux/sunrpc/svc_xprt.h
View file

@ -131,7 +131,6 @@ int svc_create_xprt(struct svc_serv *, const char *, struct net *,
const int, const unsigned short, int, const int, const unsigned short, int,
const struct cred *); const struct cred *);
void svc_xprt_received(struct svc_xprt *xprt); void svc_xprt_received(struct svc_xprt *xprt);
void svc_xprt_do_enqueue(struct svc_xprt *xprt);
void svc_xprt_enqueue(struct svc_xprt *xprt); void svc_xprt_enqueue(struct svc_xprt *xprt);
void svc_xprt_put(struct svc_xprt *xprt); void svc_xprt_put(struct svc_xprt *xprt);
void svc_xprt_copy_addrs(struct svc_rqst *rqstp, struct svc_xprt *xprt); void svc_xprt_copy_addrs(struct svc_rqst *rqstp, struct svc_xprt *xprt);

10
net/sunrpc/svc_xprt.c
View file

@ -32,6 +32,7 @@ static int svc_deferred_recv(struct svc_rqst *rqstp);
static struct cache_deferred_req *svc_defer(struct cache_req *req); static struct cache_deferred_req *svc_defer(struct cache_req *req);
static void svc_age_temp_xprts(struct timer_list *t); static void svc_age_temp_xprts(struct timer_list *t);
static void svc_delete_xprt(struct svc_xprt *xprt); static void svc_delete_xprt(struct svc_xprt *xprt);
static void svc_xprt_do_enqueue(struct svc_xprt *xprt);
/* apparently the "standard" is that clients close /* apparently the "standard" is that clients close
* idle connections after 5 minutes, servers after * idle connections after 5 minutes, servers after
@ -266,12 +267,12 @@ void svc_xprt_received(struct svc_xprt *xprt)
} }
/* As soon as we clear busy, the xprt could be closed and /* As soon as we clear busy, the xprt could be closed and
* 'put', so we need a reference to call svc_enqueue_xprt with: * 'put', so we need a reference to call svc_xprt_do_enqueue with:
*/ */
svc_xprt_get(xprt); svc_xprt_get(xprt);
smp_mb__before_atomic(); smp_mb__before_atomic();
clear_bit(XPT_BUSY, &xprt->xpt_flags); clear_bit(XPT_BUSY, &xprt->xpt_flags);
xprt->xpt_server->sv_ops->svo_enqueue_xprt(xprt); svc_xprt_do_enqueue(xprt);
svc_xprt_put(xprt); svc_xprt_put(xprt);
} }
EXPORT_SYMBOL_GPL(svc_xprt_received); EXPORT_SYMBOL_GPL(svc_xprt_received);
@ -423,7 +424,7 @@ static bool svc_xprt_ready(struct svc_xprt *xprt)
return false; return false;
} }
void svc_xprt_do_enqueue(struct svc_xprt *xprt) static void svc_xprt_do_enqueue(struct svc_xprt *xprt)
{ {
struct svc_pool *pool; struct svc_pool *pool;
struct svc_rqst *rqstp = NULL; struct svc_rqst *rqstp = NULL;
@ -467,7 +468,6 @@ out_unlock:
put_cpu(); put_cpu();
trace_svc_xprt_enqueue(xprt, rqstp); trace_svc_xprt_enqueue(xprt, rqstp);
} }
EXPORT_SYMBOL_GPL(svc_xprt_do_enqueue);
/* /*
* Queue up a transport with data pending. If there are idle nfsd * Queue up a transport with data pending. If there are idle nfsd
@ -478,7 +478,7 @@ void svc_xprt_enqueue(struct svc_xprt *xprt)
{ {
if (test_bit(XPT_BUSY, &xprt->xpt_flags)) if (test_bit(XPT_BUSY, &xprt->xpt_flags))
return; return;
xprt->xpt_server->sv_ops->svo_enqueue_xprt(xprt); svc_xprt_do_enqueue(xprt);
} }
EXPORT_SYMBOL_GPL(svc_xprt_enqueue); EXPORT_SYMBOL_GPL(svc_xprt_enqueue);