[PATCH] SUNRPC: Refresh rq_pages using a bulk page allocator
From: Chuck Lever <hidden>
Date: 2021-03-12 21:57:56
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 <redacted> --- 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() */