> On Mar 11, 2021, at 6:49 AM, Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> wrote:
>
> From: Chuck Lever <chuck.lever@xxxxxxxxxx>
>
> Reduce the rate at which nfsd threads hammer on the page allocator.
> This improve throughput scalability by enabling the threads to run
> more independently of each other.
Mel, if you should repost this series: ^improve^improves
> Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
> Signed-off-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
> ---
> net/sunrpc/svc_xprt.c | 43 +++++++++++++++++++++++++++++++------------
> 1 file changed, 31 insertions(+), 12 deletions(-)
>
> diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
> index cfa7e4776d0e..38a8d6283801 100644
> --- a/net/sunrpc/svc_xprt.c
> +++ b/net/sunrpc/svc_xprt.c
> @@ -642,11 +642,12 @@ 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;
> 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",
> @@ -654,19 +655,28 @@ 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, needed, &list);
> + for (i = 0; i < pages; i++) {
> + if (!rqstp->rq_pages[i]) {
> + 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() */
>
> @@ -681,6 +691,15 @@ 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:
> + set_current_state(TASK_INTERRUPTIBLE);
> + if (signalled() || kthread_should_stop()) {
> + set_current_state(TASK_RUNNING);
> + return -EINTR;
> + }
> + schedule_timeout(msecs_to_jiffies(500));
> + goto retry;
> }
>
> static bool
> --
> 2.26.2
>
--
Chuck Lever
