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[70.77.216.213]) by smtp.gmail.com with ESMTPSA id a13sm3652812pfn.104.2019.08.29.12.06.23 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 29 Aug 2019 12:06:24 -0700 (PDT) From: Andreas Dilger Message-Id: <8C1DC2C7-4389-446D-8233-EEDAAD38C398@dilger.ca> Content-Type: multipart/signed; boundary="Apple-Mail=_592A6161-C825-4B2C-9BAF-636BE3FA930F"; protocol="application/pgp-signature"; micalg=pgp-sha256 Mime-Version: 1.0 (Mac OS X Mail 10.3 \(3273\)) Subject: Re: [PATCH 0/3] Revert parallel dio reads Date: Thu, 29 Aug 2019 13:06:22 -0600 In-Reply-To: <20190829105858.GA22939@quack2.suse.cz> Cc: Dave Chinner , Joseph Qi , Theodore Ts'o , linux-ext4@vger.kernel.org To: Jan Kara References: <1566871552-60946-1-git-send-email-joseph.qi@linux.alibaba.com> <20190827115118.GY7777@dread.disaster.area> <20190829105858.GA22939@quack2.suse.cz> X-Mailer: Apple Mail (2.3273) Sender: linux-ext4-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org --Apple-Mail=_592A6161-C825-4B2C-9BAF-636BE3FA930F Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=us-ascii On Aug 29, 2019, at 4:58 AM, Jan Kara wrote: >=20 > On Tue 27-08-19 21:51:18, Dave Chinner wrote: >> On Tue, Aug 27, 2019 at 10:05:49AM +0800, Joseph Qi wrote: >>> This patch set is trying to revert parallel dio reads feature at = present >>> since it causes significant performance regression in mixed random >>> read/write scenario. >>>=20 >>> Joseph Qi (3): >>> Revert "ext4: remove EXT4_STATE_DIOREAD_LOCK flag" >>> Revert "ext4: fix off-by-one error when writing back pages before = dio >>> read" >>> Revert "ext4: Allow parallel DIO reads" >>>=20 >>> fs/ext4/ext4.h | 17 +++++++++++++++++ >>> fs/ext4/extents.c | 19 ++++++++++++++----- >>> fs/ext4/inode.c | 47 = +++++++++++++++++++++++++++++++---------------- >>> fs/ext4/ioctl.c | 4 ++++ >>> fs/ext4/move_extent.c | 4 ++++ >>> fs/ext4/super.c | 12 +++++++----- >>> 6 files changed, 77 insertions(+), 26 deletions(-) >>=20 >> Before doing this, you might want to have a chat and co-ordinate >> with the folks that are currently trying to port the ext4 direct IO >> code to use the iomap infrastructure: >>=20 >> = https://lore.kernel.org/linux-ext4/20190827095221.GA1568@poseidon.bobrowsk= i.net/T/#t >>=20 >> That is going to need the shared locking on read and will work just >> fine with shared locking on write, too (it's the code that XFS uses >> for direct IO). So it might be best here if you work towards shared >> locking on the write side rather than just revert the shared locking >> on the read side.... >=20 > Yeah, after converting ext4 DIO path to iomap infrastructure, using = shared > inode lock for all aligned non-extending DIO writes will be easy so = I'd > prefer if we didn't have to redo the iomap conversion patches due to = these > reverts. But if the next kernel is LTS and the iomap implementation isn't in the current merge window (very unlikely) then we're stuck with this = performance hit for LTS. It is also unlikely that LTS will take the revert patches = if they have not been landed to master. Cheers, Andreas --Apple-Mail=_592A6161-C825-4B2C-9BAF-636BE3FA930F Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename=signature.asc Content-Type: application/pgp-signature; name=signature.asc Content-Description: Message signed with OpenPGP -----BEGIN PGP SIGNATURE----- Comment: GPGTools - http://gpgtools.org iQIzBAEBCAAdFiEEDb73u6ZejP5ZMprvcqXauRfMH+AFAl1oIi4ACgkQcqXauRfM H+AKuRAAkEpkGPQX4FiwgsuMAYtQQuyLKj3fIRw1ziq+G5Q4Y98g9Lv8u4dPTpao PfOu14uAxekYtSx9avzsnhegGAMwCbYH7MT35VZ2yj4Zs59S1vWS67S2FWSRDnIk UThMXGR2BVjADjDuHN6DOyWnZTfr+a7icrFOhYvIjDyDImqmSJp2akdNhwq4MGu2 yniILeZo4GrUnMUpyAh8iqWi9tP1f5/Ix8icr+95WhmcfX4qyqJCgTUBx2DssClz G+AkgAe3rc8e9qRjehVR7vo4gGg9o6tW8IOR9dP0C1OTa9mi0qatSis+4+m+VAIU 1r8CNrXdhFSq4nza4+eahSZnZqE6BAi6yGpPdyvdYt+MzvOId0qoZaBDBCV1g0sW vvajmTqnyKoG/AM2pmMEjOsygWvewwXhQVMUDPDVQ+GTH6T67TB9xTP+wJFqCIUI 3JWKkygEiT927BPf3LZ7aAp8hbFQDinnx26Ki8E+K9Cith/EJUmLhbTUA/w3sbJP qknT2IHxJw/icTgXK7kU1N9pxKNg9xgXU9XeO63ED8PzJmdB50EjTuvfI68r+YVs EJ3fLcylZnkL8JfUB7unTMRoccg8Bhq/L19c0o0kvMk6mHfITbIJlugaVSa0CBms 6KZVUx/n5bcgQLjIRmoq5DmleNCVjUuv8EGoZP/bEag7jDOZdgA= =wBmG -----END PGP SIGNATURE----- --Apple-Mail=_592A6161-C825-4B2C-9BAF-636BE3FA930F--