Commit df971cd8 authored by Chuck Lever's avatar Chuck Lever
Browse files

svcrdma: Convert rdma_stat_recv to a per-CPU counter 



Receives are frequent events. Avoid the overhead of a memory bus
lock cycle for counting a value that is hardly every used.

Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
parent 59a00257

include/linux/sunrpc/svc_rdma.h

+2 −1
Original line number Diff line number Diff line
@@ -49,6 +49,7 @@ 
#include <linux/sunrpc/rpc_rdma_cid.h>

#include <linux/sunrpc/svc_rdma_pcl.h>



#include <linux/percpu_counter.h>

#include <rdma/ib_verbs.h>

#include <rdma/rdma_cm.h>
@@ -65,7 +66,7 @@ extern unsigned int svcrdma_max_requests; 
extern unsigned int svcrdma_max_bc_requests;

extern unsigned int svcrdma_max_req_size;



extern atomic_t rdma_stat_recv;

extern struct percpu_counter svcrdma_stat_recv;

extern atomic_t rdma_stat_read;

extern atomic_t rdma_stat_write;

extern atomic_t rdma_stat_sq_starve;

net/sunrpc/xprtrdma/svc_rdma.c

+51 −4
Original line number Diff line number Diff line
@@ -63,7 +63,7 @@ unsigned int svcrdma_max_req_size = RPCRDMA_DEF_INLINE_THRESH; 
static unsigned int min_max_inline = RPCRDMA_DEF_INLINE_THRESH;

static unsigned int max_max_inline = RPCRDMA_MAX_INLINE_THRESH;



atomic_t rdma_stat_recv;

struct percpu_counter svcrdma_stat_recv;

atomic_t rdma_stat_read;

atomic_t rdma_stat_write;

atomic_t rdma_stat_sq_starve;
@@ -110,6 +110,42 @@ static int read_reset_stat(struct ctl_table *table, int write, 
	return 0;

}



enum {

	SVCRDMA_COUNTER_BUFSIZ	= sizeof(unsigned long long),

};



static int svcrdma_counter_handler(struct ctl_table *table, int write,

				   void *buffer, size_t *lenp, loff_t *ppos)

{

	struct percpu_counter *stat = (struct percpu_counter *)table->data;

	char tmp[SVCRDMA_COUNTER_BUFSIZ + 1];

	int len;



	if (write) {

		percpu_counter_set(stat, 0);

		return 0;

	}



	len = snprintf(tmp, SVCRDMA_COUNTER_BUFSIZ, "%lld\n",

		       percpu_counter_sum_positive(stat));

	if (len >= SVCRDMA_COUNTER_BUFSIZ)

		return -EFAULT;

	len = strlen(tmp);

	if (*ppos > len) {

		*lenp = 0;

		return 0;

	}

	len -= *ppos;

	if (len > *lenp)

		len = *lenp;

	if (len)

		memcpy(buffer, tmp, len);

	*lenp = len;

	*ppos += len;



	return 0;

}



static struct ctl_table_header *svcrdma_table_header;

static struct ctl_table svcrdma_parm_table[] = {

	{
@@ -149,10 +185,10 @@ static struct ctl_table svcrdma_parm_table[] = { 
	},

	{

		.procname	= "rdma_stat_recv",

		.data		= &rdma_stat_recv,

		.maxlen		= sizeof(atomic_t),

		.data		= &svcrdma_stat_recv,

		.maxlen		= SVCRDMA_COUNTER_BUFSIZ,

		.mode		= 0644,

		.proc_handler	= read_reset_stat,

		.proc_handler	= svcrdma_counter_handler,

	},

	{

		.procname	= "rdma_stat_write",
@@ -230,15 +266,26 @@ static void svc_rdma_proc_cleanup(void) 
		return;

	unregister_sysctl_table(svcrdma_table_header);

	svcrdma_table_header = NULL;



	percpu_counter_destroy(&svcrdma_stat_recv);

}



static int svc_rdma_proc_init(void)

{

	int rc;



	if (svcrdma_table_header)

		return 0;



	rc = percpu_counter_init(&svcrdma_stat_recv, 0, GFP_KERNEL);

	if (rc)

		goto out_err;



	svcrdma_table_header = register_sysctl_table(svcrdma_root_table);

	return 0;



out_err:

	return rc;

}



void svc_rdma_cleanup(void)

net/sunrpc/xprtrdma/svc_rdma_recvfrom.c

+1 −2
Original line number Diff line number Diff line
@@ -845,8 +845,7 @@ int svc_rdma_recvfrom(struct svc_rqst *rqstp) 
	}

	list_del(&ctxt->rc_list);

	spin_unlock(&rdma_xprt->sc_rq_dto_lock);



	atomic_inc(&rdma_stat_recv);

	percpu_counter_inc(&svcrdma_stat_recv);



	svc_rdma_build_arg_xdr(rqstp, ctxt);