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authorChuck Lever <chuck.lever@oracle.com>2021-04-30 09:01:58 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2021-04-30 21:20:43 +0300
commitab8362645fba90fa44ec1991ad05544e307dd02f (patch)
treea8dabb99d92429d2d3d33b2afeb06251a766ac3d /net/sunrpc
parent3b822017b636bf4261a644c16b01eb3900f2a9a0 (diff)
downloadlinux-ab8362645fba90fa44ec1991ad05544e307dd02f.tar.xz
SUNRPC: set rq_page_end differently
Patch series "SUNRPC consumer for the bulk page allocator" This patch set and the measurements below are based on yesterday's bulk allocator series: git://git.kernel.org/pub/scm/linux/kernel/git/mel/linux.git mm-bulk-rebase-v5r9 The patches change SUNRPC to invoke the array-based bulk allocator instead of alloc_page(). The micro-benchmark results are promising. I ran a mixture of 256KB reads and writes over NFSv3. The server's kernel is built with KASAN enabled, so the comparison is exaggerated but I believe it is still valid. I instrumented svc_recv() to measure the latency of each call to svc_alloc_arg() and report it via a trace point. The following results are averages across the trace events. Single page: 25.007 us per call over 532,571 calls Bulk list: 6.258 us per call over 517,034 calls Bulk array: 4.590 us per call over 517,442 calls This patch (of 2) Refactor: I'm about to use the loop variable @i for something else. As far as the "i++" is concerned, that is a post-increment. The value of @i is not used subsequently, so the increment operator is unnecessary and can be removed. Also note that nfsd_read_actor() was renamed nfsd_splice_actor() by commit cf8208d0eabd ("sendfile: convert nfsd to splice_direct_to_actor()"). Link: https://lkml.kernel.org/r/20210325114228.27719-7-mgorman@techsingularity.net Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Reviewed-by: Alexander Lobakin <alobakin@pm.me> Cc: Alexander Duyck <alexander.duyck@gmail.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: David Miller <davem@davemloft.net> Cc: Ilias Apalodimas <ilias.apalodimas@linaro.org> Cc: Jesper Dangaard Brouer <brouer@redhat.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'net/sunrpc')
-rw-r--r--net/sunrpc/svc_xprt.c7
1 files changed, 3 insertions, 4 deletions
diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
index 42565f0c7d5a..63eb6b9a4973 100644
--- a/net/sunrpc/svc_xprt.c
+++ b/net/sunrpc/svc_xprt.c
@@ -661,7 +661,7 @@ 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;
- struct xdr_buf *arg;
+ struct xdr_buf *arg = &rqstp->rq_arg;
int pages;
int i;
@@ -686,11 +686,10 @@ static int svc_alloc_arg(struct svc_rqst *rqstp)
}
rqstp->rq_pages[i] = p;
}
- rqstp->rq_page_end = &rqstp->rq_pages[i];
- rqstp->rq_pages[i++] = NULL; /* this might be seen in nfs_read_actor */
+ rqstp->rq_page_end = &rqstp->rq_pages[pages];
+ rqstp->rq_pages[pages] = NULL; /* this might be seen in nfsd_splice_actor() */
/* Make arg->head point to first page and arg->pages point to rest */
- arg = &rqstp->rq_arg;
arg->head[0].iov_base = page_address(rqstp->rq_pages[0]);
arg->head[0].iov_len = PAGE_SIZE;
arg->pages = rqstp->rq_pages + 1;