[PATCH RFC] SUNRPC: Refresh rq_pages using a bulk page allocator
From: Chuck Lever <chuck.lever@oracle.com>
Date: 2021-02-15 16:06:11
Also in:
linux-mm
Subsystem:
kernel nfsd, sunrpc, and lockd servers, networking [general], nfs, sunrpc, and lockd clients, the rest · Maintainers:
Chuck Lever, Jeff Layton, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Trond Myklebust, Anna Schumaker, Linus Torvalds
Reduce the rate at which nfsd threads hammer on the page allocator. This improves throughput scalability by enabling the nfsd threads to run more independently of each other. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> --- net/sunrpc/svc_xprt.c | 44 ++++++++++++++++++++++++++++++++------------ 1 file changed, 32 insertions(+), 12 deletions(-) Note: I haven't actually tried the "min_t(needed, 13)" bit yet.
diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
index 4730bac409b5..8f398179d818 100644
--- a/net/sunrpc/svc_xprt.c
+++ b/net/sunrpc/svc_xprt.c@@ -647,11 +647,11 @@ 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; 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",
@@ -659,19 +659,33 @@ 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++; + if (needed) { + LIST_HEAD(list); + +retry: + alloc_pages_bulk(GFP_KERNEL, 0, + /* to test the retry logic: */ + min_t(unsigned long, needed, 13), + &list); + for (i = 0; i < pages; i++) { + if (!rqstp->rq_pages[i]) { + struct page *page; + + page = list_first_entry_or_null(&list, + struct page, + lru); + if (unlikely(!page)) + goto empty_list; + list_del(&page->lru); + rqstp->rq_pages[i] = page; + needed--; } - rqstp->rq_pages[i] = p; } + } rqstp->rq_page_end = &rqstp->rq_pages[pages]; rqstp->rq_pages[pages] = NULL; /* this might be seen in nfsd_splice_actor() */
@@ -686,6 +700,12 @@ static int svc_alloc_arg(struct svc_rqst *rqstp) arg->len = (pages-1)*PAGE_SIZE; arg->tail[0].iov_len = 0; return 0; + +empty_list: + if (signalled() || kthread_should_stop()) + return -EINTR; + cond_resched(); + goto retry; } static bool