Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S938635AbcJQRaI (ORCPT ); Mon, 17 Oct 2016 13:30:08 -0400 Received: from mga11.intel.com ([192.55.52.93]:20503 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933945AbcJQR37 (ORCPT ); Mon, 17 Oct 2016 13:29:59 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.31,357,1473145200"; d="scan'208";a="20898900" Date: Mon, 17 Oct 2016 11:29:57 -0600 From: Ross Zwisler To: Toshi Kani Cc: akpm@linux-foundation.org, dan.j.williams@intel.com, viro@zeniv.linux.org.uk, ross.zwisler@linux.intel.com, linux-nvdimm@ml01.01.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] DAX: enable iostat for read/write Message-ID: <20161017172957.GC25175@linux.intel.com> Mail-Followup-To: Ross Zwisler , Toshi Kani , akpm@linux-foundation.org, dan.j.williams@intel.com, viro@zeniv.linux.org.uk, linux-nvdimm@lists.01.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org References: <1476724738-19133-1-git-send-email-toshi.kani@hpe.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1476724738-19133-1-git-send-email-toshi.kani@hpe.com> User-Agent: Mutt/1.7.0 (2016-08-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3044 Lines: 93 On Mon, Oct 17, 2016 at 11:18:58AM -0600, Toshi Kani wrote: > DAX IO path does not support iostat, but its metadata IO path does. > Therefore, iostat shows metadata IO statistics only, which has been > confusing to users. > > Add iostat support to the DAX read/write path. > > Note, iostat still does not support the DAX mmap path as it allows > user applications to access directly. > > Signed-off-by: Toshi Kani > Cc: Andrew Morton > Cc: Alexander Viro > Cc: Dan Williams > Cc: Ross Zwisler > --- > v2: > - Set a minimum of one sector (Dan Williams) What about Dave's feedback that this code just reimplements generic_start_io_acct() and generic_end_io_acct()? > --- > fs/dax.c | 37 +++++++++++++++++++++++++++++++++++++ > 1 file changed, 37 insertions(+) > > diff --git a/fs/dax.c b/fs/dax.c > index 014defd..43e5e7a 100644 > --- a/fs/dax.c > +++ b/fs/dax.c > @@ -144,6 +144,34 @@ static sector_t to_sector(const struct buffer_head *bh, > return sector; > } > > +static void dax_iostat_start(struct gendisk *disk, struct iov_iter *iter, > + unsigned long *start) > +{ > + int rw = iov_iter_rw(iter); > + int sec = iov_iter_count(iter) >> 9; > + int cpu = part_stat_lock(); > + > + *start = jiffies; > + part_round_stats(cpu, &disk->part0); > + part_stat_inc(cpu, &disk->part0, ios[rw]); > + part_stat_add(cpu, &disk->part0, sectors[rw], ((!sec) ? 1 : sec)); > + part_inc_in_flight(&disk->part0, rw); > + part_stat_unlock(); > +} > + > +static void dax_iostat_end(struct gendisk *disk, struct iov_iter *iter, > + unsigned long start) > +{ > + unsigned long duration = jiffies - start; > + int rw = iov_iter_rw(iter); > + int cpu = part_stat_lock(); > + > + part_stat_add(cpu, &disk->part0, ticks[rw], duration); > + part_round_stats(cpu, &disk->part0); > + part_dec_in_flight(&disk->part0, rw); > + part_stat_unlock(); > +} > + > static ssize_t dax_io(struct inode *inode, struct iov_iter *iter, > loff_t start, loff_t end, get_block_t get_block, > struct buffer_head *bh) > @@ -265,9 +293,12 @@ ssize_t dax_do_io(struct kiocb *iocb, struct inode *inode, > ssize_t retval = -EINVAL; > loff_t pos = iocb->ki_pos; > loff_t end = pos + iov_iter_count(iter); > + struct gendisk *disk; > + unsigned long start = 0; > > memset(&bh, 0, sizeof(bh)); > bh.b_bdev = inode->i_sb->s_bdev; > + disk = bh.b_bdev->bd_disk; > > if ((flags & DIO_LOCKING) && iov_iter_rw(iter) == READ) > inode_lock(inode); > @@ -276,8 +307,14 @@ ssize_t dax_do_io(struct kiocb *iocb, struct inode *inode, > if (!(flags & DIO_SKIP_DIO_COUNT)) > inode_dio_begin(inode); > > + if (blk_queue_io_stat(disk->queue)) > + dax_iostat_start(disk, iter, &start); > + > retval = dax_io(inode, iter, pos, end, get_block, &bh); > > + if (start) > + dax_iostat_end(disk, iter, start); > + > if ((flags & DIO_LOCKING) && iov_iter_rw(iter) == READ) > inode_unlock(inode); >