Reduce the rate at which nfsd threads hammer on the page allocator.
This improves throughput scalability by enabling the threads to run
more independently of each other.
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
---
Hi Mel-
This patch replaces patch 5/7 in v4 of your alloc_pages_bulk()
series. It implements code clean-ups suggested by Alexander Duyck.
It builds and has seen some light testing.
net/sunrpc/svc_xprt.c | 39 +++++++++++++++++++++++++++------------
1 file changed, 27 insertions(+), 12 deletions(-)
diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
index 4d58424db009..791ea24159b1 100644
--- a/net/sunrpc/svc_xprt.c
+++ b/net/sunrpc/svc_xprt.c
@@ -661,11 +661,13 @@ static void svc_check_conn_limits(struct svc_serv *serv)
static int svc_alloc_arg(struct svc_rqst *rqstp)
{
struct svc_serv *serv = rqstp->rq_server;
+ unsigned long needed;
struct xdr_buf *arg;
+ struct page *page;
+ LIST_HEAD(list);
int pages;
int i;
- /* now allocate needed pages. If we get a failure, sleep briefly */
pages = (serv->sv_max_mesg + 2 * PAGE_SIZE) >> PAGE_SHIFT;
if (pages > RPCSVC_MAXPAGES) {
pr_warn_once("svc: warning: pages=%u > RPCSVC_MAXPAGES=%lu\n",
@@ -673,19 +675,32 @@ static int svc_alloc_arg(struct svc_rqst *rqstp)
/* use as many pages as possible */
pages = RPCSVC_MAXPAGES;
}
- for (i = 0; i < pages ; i++)
- while (rqstp->rq_pages[i] == NULL) {
- struct page *p = alloc_page(GFP_KERNEL);
- if (!p) {
- set_current_state(TASK_INTERRUPTIBLE);
- if (signalled() || kthread_should_stop()) {
- set_current_state(TASK_RUNNING);
- return -EINTR;
- }
- schedule_timeout(msecs_to_jiffies(500));
+
+ for (needed = 0, i = 0; i < pages ; i++) {
+ if (!rqstp->rq_pages[i])
+ needed++;
+ }
+ i = 0;
+ while (needed) {
+ needed -= alloc_pages_bulk(GFP_KERNEL, 0, needed, &list);
+ for (; i < pages; i++) {
+ if (rqstp->rq_pages[i])
+ continue;
+ page = list_first_entry_or_null(&list, struct page, lru);
+ if (likely(page)) {
+ list_del(&page->lru);
+ rqstp->rq_pages[i] = page;
+ continue;
}
- rqstp->rq_pages[i] = p;
+ set_current_state(TASK_INTERRUPTIBLE);
+ if (signalled() || kthread_should_stop()) {
+ set_current_state(TASK_RUNNING);
+ return -EINTR;
+ }
+ schedule_timeout(msecs_to_jiffies(500));
+ break;
}
+ }
rqstp->rq_page_end = &rqstp->rq_pages[pages];
rqstp->rq_pages[pages] = NULL; /* this might be seen in nfsd_splice_actor() */
