> On Mar 23, 2021, at 3:56 PM, Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> wrote:
>
> On Tue, Mar 23, 2021 at 11:10:05AM -0400, Chuck Lever wrote:
>> 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>
>
> I've picked up the series and merged the leader with the first patch
> because I think the array vs list data is interesting but I did change
> the patch.
>
>> + for (;;) {
>> + filled = alloc_pages_bulk_array(GFP_KERNEL, pages,
>> + rqstp->rq_pages);
>> + /* We assume that if the next array element is populated,
>> + * all the following elements are as well, thus we're done. */
>> + if (filled == pages || rqstp->rq_pages[filled])
>> + break;
>> +
>
> I altered this check because the implementation now returns a useful
> index. I know I had concerns about this but while the implementation
> cost is higher, the caller needs less knowledge of alloc_bulk_pages
> implementation. It might be unfortunate if new users all had to have
> their own optimisations around hole management so lets keep it simpler
> to start with.
Agreed! Your version below looks like what I'm testing now --
the "rq_pages[filled]" test and the comment have been removed.
> Version current in my tree is below but also available in
>
> git://git.kernel.org/pub/scm/linux/kernel/git/mel/linux.git mm-bulk-rebase-v6r5
>
> ---8<---
> SUNRPC: Refresh rq_pages using a bulk page allocator
>
> From: Chuck Lever <chuck.lever@xxxxxxxxxx>
>
> 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.
>
> [mgorman: Update interpretation of alloc_pages_bulk return value]
> Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
> Signed-off-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
> ---
> net/sunrpc/svc_xprt.c | 31 +++++++++++++++----------------
> 1 file changed, 15 insertions(+), 16 deletions(-)
>
> diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
> index 609bda97d4ae..0c27c3291ca1 100644
> --- a/net/sunrpc/svc_xprt.c
> +++ b/net/sunrpc/svc_xprt.c
> @@ -643,30 +643,29 @@ static int svc_alloc_arg(struct svc_rqst *rqstp)
> {
> struct svc_serv *serv = rqstp->rq_server;
> struct xdr_buf *arg = &rqstp->rq_arg;
> - int pages;
> - int i;
> + unsigned long pages, filled;
>
> - /* 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",
> + pr_warn_once("svc: warning: pages=%lu > RPCSVC_MAXPAGES=%lu\n",
> pages, RPCSVC_MAXPAGES);
> /* 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));
> - }
> - rqstp->rq_pages[i] = p;
> +
> + for (;;) {
> + filled = alloc_pages_bulk_array(GFP_KERNEL, pages,
> + rqstp->rq_pages);
> + if (filled == pages)
> + break;
> +
> + set_current_state(TASK_INTERRUPTIBLE);
> + if (signalled() || kthread_should_stop()) {
> + set_current_state(TASK_RUNNING);
> + return -EINTR;
> }
> + schedule_timeout(msecs_to_jiffies(500));
> + }
> rqstp->rq_page_end = &rqstp->rq_pages[pages];
> rqstp->rq_pages[pages] = NULL; /* this might be seen in nfsd_splice_actor() */
>
--
Chuck Lever
