From: Al Viro <viro@zeniv.linux.org.uk>
To: Chuck Lever III <chuck.lever@oracle.com>
Cc: Linux NFS Mailing List <linux-nfs@vger.kernel.org>,
netdev <netdev@vger.kernel.org>,
Dave Chinner <david@fromorbit.com>,
"tgraf@suug.ch" <tgraf@suug.ch>, Jeff Layton <jlayton@redhat.com>
Subject: Re: [PATCH RFC 28/30] NFSD: Set up an rhashtable for the filecache
Date: Fri, 24 Jun 2022 01:29:32 +0100 [thread overview]
Message-ID: <YrUFbLJ5uVbWtZbf@ZenIV> (raw)
In-Reply-To: <4417FB68-83C9-43DC-BB57-122D405302E7@oracle.com>
On Fri, Jun 24, 2022 at 12:14:53AM +0000, Chuck Lever III wrote:
>
> > On Jun 23, 2022, at 7:51 PM, Chuck Lever III <chuck.lever@oracle.com> wrote:
> >
> >> On Jun 23, 2022, at 6:56 PM, Al Viro <viro@zeniv.linux.org.uk> wrote:
> >>
> >> On Wed, Jun 22, 2022 at 10:15:50AM -0400, Chuck Lever wrote:
> >>
> >>> +static u32 nfsd_file_obj_hashfn(const void *data, u32 len, u32 seed)
> >>> +{
> >>> + const struct nfsd_file *nf = data;
> >>> +
> >>> + return jhash2((const u32 *)&nf->nf_inode,
> >>> + sizeof_field(struct nfsd_file, nf_inode) / sizeof(u32),
> >>> + seed);
> >>
> >> Out of curiosity - what are you using to allocate those? Because if
> >> it's a slab, then middle bits of address (i.e. lower bits of
> >> (unsigned long)data / L1_CACHE_BYTES) would better be random enough...
> >
> > 261 static struct nfsd_file *
> > 262 nfsd_file_alloc(struct nfsd_file_lookup_key *key, unsigned int may)
> > 263 {
> > 264 static atomic_t nfsd_file_id;
> > 265 struct nfsd_file *nf;
> > 266
> > 267 nf = kmem_cache_alloc(nfsd_file_slab, GFP_KERNEL);
> >
> > Was wondering about that. pahole says struct nfsd_file is 112
> > bytes on my system.
>
> Oops. nfsd_file_obj_hashfn() is supposed to be generating the
> hash value based on the address stored in the nf_inode field.
> So it's an inode pointer, alloced via kmem_cache_alloc by default.
inode pointers are definitely "divide by L1_CACHE_BYTES and take lower
bits" fodder...
next prev parent reply other threads:[~2022-06-24 0:29 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-06-22 14:12 [PATCH RFC 00/30] Overhaul NFSD filecache Chuck Lever
2022-06-22 14:12 ` [PATCH RFC 01/30] NFSD: Report filecache LRU size Chuck Lever
2022-06-22 14:12 ` [PATCH RFC 02/30] NFSD: Report count of calls to nfsd_file_acquire() Chuck Lever
2022-06-22 14:13 ` [PATCH RFC 03/30] NFSD: Report count of freed filecache items Chuck Lever
2022-06-22 14:13 ` [PATCH RFC 04/30] NFSD: Report average age of " Chuck Lever
2022-06-22 14:13 ` [PATCH RFC 05/30] NFSD: Add nfsd_file_lru_dispose_list() helper Chuck Lever
2022-06-22 14:13 ` [PATCH RFC 06/30] NFSD: Refactor nfsd_file_gc() Chuck Lever
2022-06-22 14:13 ` [PATCH RFC 07/30] NFSD: Refactor nfsd_file_lru_scan() Chuck Lever
2022-06-22 14:13 ` [PATCH RFC 08/30] NFSD: Report the number of items evicted by the LRU walk Chuck Lever
2022-06-22 14:13 ` [PATCH RFC 09/30] NFSD: Record number of flush calls Chuck Lever
2022-06-22 14:13 ` [PATCH RFC 10/30] NFSD: Report filecache item construction failures Chuck Lever
2022-06-22 14:13 ` [PATCH RFC 11/30] NFSD: Zero counters when the filecache is re-initialized Chuck Lever
2022-06-22 14:14 ` [PATCH RFC 12/30] NFSD: Hook up the filecache stat file Chuck Lever
2022-06-22 14:14 ` [PATCH RFC 13/30] NFSD: WARN when freeing an item still linked via nf_lru Chuck Lever
2022-06-22 14:14 ` [PATCH RFC 14/30] NFSD: Trace filecache LRU activity Chuck Lever
2022-06-22 14:14 ` [PATCH RFC 15/30] NFSD: Leave open files out of the filecache LRU Chuck Lever
2022-06-22 14:14 ` [PATCH RFC 16/30] NFSD: Fix the filecache LRU shrinker Chuck Lever
2022-06-22 14:14 ` [PATCH RFC 17/30] NFSD: Never call nfsd_file_gc() in foreground paths Chuck Lever
2022-06-22 14:14 ` [PATCH RFC 18/30] NFSD: No longer record nf_hashval in the trace log Chuck Lever
2022-06-22 14:14 ` [PATCH RFC 19/30] NFSD: Remove lockdep assertion from unhash_and_release_locked() Chuck Lever
2022-06-22 14:14 ` [PATCH RFC 20/30] NFSD: nfsd_file_unhash can compute hashval from nf->nf_inode Chuck Lever
2022-06-22 14:15 ` [PATCH RFC 21/30] NFSD: Refactor __nfsd_file_close_inode() Chuck Lever
2022-06-22 14:15 ` [PATCH RFC 22/30] NFSD: nfsd_file_hash_remove can compute hashval Chuck Lever
2022-06-22 14:15 ` [PATCH RFC 23/30] NFSD: Remove nfsd_file::nf_hashval Chuck Lever
2022-06-22 14:15 ` [PATCH RFC 24/30] NFSD: Remove stale comment from nfsd_file_acquire() Chuck Lever
2022-06-22 14:15 ` [PATCH RFC 25/30] NFSD: Clean up "open file" case in nfsd_file_acquire() Chuck Lever
2022-06-22 14:15 ` [PATCH RFC 26/30] NFSD: Document nfsd_file_cache_purge() API contract Chuck Lever
2022-06-22 14:15 ` [PATCH RFC 27/30] NFSD: Replace the "init once" mechanism Chuck Lever
2022-06-22 14:15 ` [PATCH RFC 28/30] NFSD: Set up an rhashtable for the filecache Chuck Lever
2022-06-23 22:56 ` Al Viro
2022-06-23 23:51 ` Chuck Lever III
2022-06-24 0:14 ` Chuck Lever III
2022-06-24 0:29 ` Al Viro [this message]
2022-06-22 14:15 ` [PATCH RFC 29/30] NFSD: Convert the filecache to use rhashtable Chuck Lever
2022-06-23 0:38 ` Dave Chinner
2022-06-23 0:58 ` Chuck Lever III
2022-06-23 17:27 ` Chuck Lever III
2022-06-23 22:33 ` Dave Chinner
2022-06-23 23:59 ` Chuck Lever III
2022-06-22 14:16 ` [PATCH RFC 30/30] NFSD: Clean up unusued code after rhashtable conversion Chuck Lever
2022-06-22 18:36 ` [PATCH RFC 00/30] Overhaul NFSD filecache Wang Yugui
2022-06-22 19:04 ` Chuck Lever III
2022-06-22 19:59 ` Chuck Lever III
2022-06-23 9:02 ` Wang Yugui
2022-06-23 16:44 ` Chuck Lever III
2022-06-23 17:51 ` Wang Yugui
2022-06-24 15:30 ` Chuck Lever III
2022-06-23 0:21 ` Dave Chinner
2022-06-23 1:01 ` Chuck Lever III
2022-06-23 20:27 ` Frank van der Linden
2022-06-28 17:57 ` Chuck Lever III
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