From 85aa8ddc3818718208c3cfdfda9c8c908c9dead1 Mon Sep 17 00:00:00 2001 From: Benjamin Coddington Date: Tue, 20 Sep 2022 13:00:21 -0400 Subject: [PATCH] NFS: Trigger the "ls -l" readdir heuristic sooner Since commit 1a34c8c9a49e ("NFS: Support larger readdir buffers") has updated dtsize, and with recent improvements to the READDIRPLUS helper heuristic, the heuristic may not trigger until many dentries are emitted to userspace. This will cause many thousands of GETATTR calls for "ls -l" when the directory's pagecache has already been populated. This manifests as poor performance for long directory listings after an initially fast "ls -l". Fix this by emitting only 17 entries for any first pass through the NFS directory's ->iterate_shared(), which allows userpace to prime the counters for the heuristic. Signed-off-by: Benjamin Coddington Signed-off-by: Trond Myklebust --- fs/nfs/dir.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c index bccb04af38aee..ea1ceffa1d3aa 100644 --- a/fs/nfs/dir.c +++ b/fs/nfs/dir.c @@ -1074,6 +1074,8 @@ static int readdir_search_pagecache(struct nfs_readdir_descriptor *desc) return res; } +#define NFS_READDIR_CACHE_MISS_THRESHOLD (16UL) + /* * Once we've found the start of the dirent within a page: fill 'er up... */ @@ -1083,6 +1085,7 @@ static void nfs_do_filldir(struct nfs_readdir_descriptor *desc, struct file *file = desc->file; struct nfs_cache_array *array; unsigned int i; + bool first_emit = !desc->dir_cookie; array = kmap_local_page(desc->page); for (i = desc->cache_entry_index; i < array->size; i++) { @@ -1106,6 +1109,10 @@ static void nfs_do_filldir(struct nfs_readdir_descriptor *desc, desc->ctx->pos = desc->dir_cookie; else desc->ctx->pos++; + if (first_emit && i > NFS_READDIR_CACHE_MISS_THRESHOLD + 1) { + desc->eob = true; + break; + } } if (array->page_is_eof) desc->eof = !desc->eob; @@ -1187,8 +1194,6 @@ out: return status; } -#define NFS_READDIR_CACHE_MISS_THRESHOLD (16UL) - static bool nfs_readdir_handle_cache_misses(struct inode *inode, struct nfs_readdir_descriptor *desc, unsigned int cache_misses, -- 2.30.2