From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay2.corp.sgi.com [137.38.102.29]) by oss.sgi.com (Postfix) with ESMTP id 499577CA4 for ; Thu, 25 Aug 2016 07:38:12 -0500 (CDT) Received: from cuda.sgi.com (cuda2.sgi.com [192.48.176.25]) by relay2.corp.sgi.com (Postfix) with ESMTP id 0487130405F for ; Thu, 25 Aug 2016 05:38:12 -0700 (PDT) Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by cuda.sgi.com with ESMTP id CZb9Wz2kGacAUlT6 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO) for ; Thu, 25 Aug 2016 05:38:11 -0700 (PDT) Date: Thu, 25 Aug 2016 08:38:09 -0400 From: Brian Foster Subject: Re: [PATCH 3/4] xfs: make xfs_inode_set_eofblocks_tag cheaper for the common case Message-ID: <20160825123808.GC25041@bfoster.bfoster> References: <1471816273-28940-1-git-send-email-hch@lst.de> <1471816273-28940-4-git-send-email-hch@lst.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1471816273-28940-4-git-send-email-hch@lst.de> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: Christoph Hellwig Cc: xfs@oss.sgi.com On Sun, Aug 21, 2016 at 11:51:12PM +0200, Christoph Hellwig wrote: > For long growing file writes we will usually already have the eofblocks > tag set when adding more speculative preallocations. Add a flag in the > inode to allow us to skip the the fairly expensive AG-wide spinlocks > and multiple radix tree operations in that case. > > Signed-off-by: Christoph Hellwig > --- > fs/xfs/xfs_icache.c | 14 ++++++++++++++ > fs/xfs/xfs_inode.h | 1 + > 2 files changed, 15 insertions(+) > > diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c > index fb39a66..65b2e3f 100644 > --- a/fs/xfs/xfs_icache.c > +++ b/fs/xfs/xfs_icache.c > @@ -1414,6 +1414,16 @@ xfs_inode_set_eofblocks_tag( > struct xfs_perag *pag; > int tagged; > > + /* > + * Don't bother locking the AG and looking up in the radix trees > + * if we already know that we have the tag set. > + */ > + if (ip->i_flags & XFS_IEOFBLOCKS) > + return; > + spin_lock(&ip->i_flags_lock); > + ip->i_flags |= XFS_IEOFBLOCKS; > + spin_unlock(&ip->i_flags_lock); > + I'm guessing the lockless check is intentional, but is that really necessary? E.g., it doesn't seem like using ->i_flags_lock unconditionally should affect performance in the way the AG lock or radix tree work does, particularly since we're already holding IOLOCK_EXCL in the current implementation. I could be wrong, but FWIW, we do already have xfs_iflags_test_and_set() sitting around as well... Brian > pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ip->i_ino)); > spin_lock(&pag->pag_ici_lock); > trace_xfs_inode_set_eofblocks_tag(ip); > @@ -1449,6 +1459,10 @@ xfs_inode_clear_eofblocks_tag( > struct xfs_mount *mp = ip->i_mount; > struct xfs_perag *pag; > > + spin_lock(&ip->i_flags_lock); > + ip->i_flags &= ~XFS_IEOFBLOCKS; > + spin_unlock(&ip->i_flags_lock); > + > pag = xfs_perag_get(mp, XFS_INO_TO_AGNO(mp, ip->i_ino)); > spin_lock(&pag->pag_ici_lock); > trace_xfs_inode_clear_eofblocks_tag(ip); > diff --git a/fs/xfs/xfs_inode.h b/fs/xfs/xfs_inode.h > index e1a411e..8f30d25 100644 > --- a/fs/xfs/xfs_inode.h > +++ b/fs/xfs/xfs_inode.h > @@ -216,6 +216,7 @@ xfs_get_initial_prid(struct xfs_inode *dp) > #define __XFS_IPINNED_BIT 8 /* wakeup key for zero pin count */ > #define XFS_IPINNED (1 << __XFS_IPINNED_BIT) > #define XFS_IDONTCACHE (1 << 9) /* don't cache the inode long term */ > +#define XFS_IEOFBLOCKS (1 << 10)/* has the preallocblocks tag set */ > > /* > * Per-lifetime flags need to be reset when re-using a reclaimable inode during > -- > 2.1.4 > > _______________________________________________ > xfs mailing list > xfs@oss.sgi.com > http://oss.sgi.com/mailman/listinfo/xfs _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs