From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753391AbbCNHA5 (ORCPT ); Sat, 14 Mar 2015 03:00:57 -0400 Received: from cantor2.suse.de ([195.135.220.15]:38479 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753171AbbCNHAz (ORCPT ); Sat, 14 Mar 2015 03:00:55 -0400 Date: Sat, 14 Mar 2015 08:00:50 +0100 From: Jan Kara To: Josef Bacik Cc: viro@ZenIV.linux.org.uk, linux-fsdevel@vger.kernel.org, david@fromorbit.com, jack@suse.cz, linux-kernel@vger.kernel.org Subject: Re: [PATCH] inode: add hlist_fake to avoid the inode hash lock in evict V2 Message-ID: <20150314070050.GF2888@quack.suse.cz> References: <20150312095206.GM29656@ZenIV.linux.org.uk> <1426162823-31760-1-git-send-email-jbacik@fb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1426162823-31760-1-git-send-email-jbacik@fb.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu 12-03-15 08:20:23, Josef Bacik wrote: > Some filesystems don't use the VFS inode hash and fake the fact they > are hashed so that all the writeback code works correctly. However, > this means the evict() path still tries to remove the inode from the > hash, meaning that the inode_hash_lock() needs to be taken > unnecessarily. Hence under certain workloads the inode_hash_lock can > be contended even if the inode is never actually hashed. > > To avoid this add hlist_fake to test if the inode isn't actually > hashed to avoid taking the hash lock on inodes that have never been > hashed. Based on Dave Chinner's > > inode: add IOP_NOTHASHED to avoid inode hash lock in evict > > basd on Al's suggestions. Thanks, > > Signed-off-by: Josef Bacik Looks good. You can add: Reviewed-by: Jan Kara Honza > --- > V1->V2: Argh sorry, forgot to reset the author, my bad. > > include/linux/fs.h | 2 +- > include/linux/list.h | 5 +++++ > 2 files changed, 6 insertions(+), 1 deletion(-) > > diff --git a/include/linux/fs.h b/include/linux/fs.h > index b4d71b5..31da757 100644 > --- a/include/linux/fs.h > +++ b/include/linux/fs.h > @@ -2528,7 +2528,7 @@ static inline void insert_inode_hash(struct inode *inode) > extern void __remove_inode_hash(struct inode *); > static inline void remove_inode_hash(struct inode *inode) > { > - if (!inode_unhashed(inode)) > + if (!inode_unhashed(inode) && !hlist_fake(&inode->i_hash)) > __remove_inode_hash(inode); > } > > diff --git a/include/linux/list.h b/include/linux/list.h > index feb773c..3e3e64a 100644 > --- a/include/linux/list.h > +++ b/include/linux/list.h > @@ -672,6 +672,11 @@ static inline void hlist_add_fake(struct hlist_node *n) > n->pprev = &n->next; > } > > +static inline bool hlist_fake(struct hlist_node *h) > +{ > + return h->pprev == &h->next; > +} > + > /* > * Move a list from one list head to another. Fixup the pprev > * reference of the first entry if it exists. > -- > 1.9.3 > -- Jan Kara SUSE Labs, CR