From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mailout-de.gmx.net ([213.165.64.22]:45955 "HELO mailout-de.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1756754Ab2IXSSr (ORCPT ); Mon, 24 Sep 2012 14:18:47 -0400 Message-ID: <5060A428.80302@gmx.net> Date: Mon, 24 Sep 2012 20:19:20 +0200 From: Arne Jansen MIME-Version: 1.0 To: Josef Bacik CC: linux-btrfs@vger.kernel.org Subject: Re: [PATCH] Btrfs: do not async metadata csums if we have hardware crc32c References: <1348510264-5781-1-git-send-email-jbacik@fusionio.com> In-Reply-To: <1348510264-5781-1-git-send-email-jbacik@fusionio.com> Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-btrfs-owner@vger.kernel.org List-ID: On 09/24/12 20:11, Josef Bacik wrote: > The reason we offload csumming is because it is CPU intensive, except it is > not on modern intel CPUs. So check to see if we support hardware crc32c, > and if we do just do the csumming in our current threads context. Otherwise > we can farm it off. Thanks, > > Signed-off-by: Josef Bacik > --- > fs/btrfs/disk-io.c | 17 +++++++++++++++++ > 1 files changed, 17 insertions(+), 0 deletions(-) > > diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c > index dcaf556..830b9af 100644 > --- a/fs/btrfs/disk-io.c > +++ b/fs/btrfs/disk-io.c > @@ -31,6 +31,7 @@ > #include > #include > #include > +#include > #include "compat.h" > #include "ctree.h" > #include "disk-io.h" > @@ -880,6 +881,22 @@ static int btree_submit_bio_hook(struct inode *inode, int rw, struct bio *bio, > } > > /* > + * Pretty sure I'm going to hell for this. If our CPU can do crc32cs in > + * the hardware then there is no reason to do the csum stuff > + * asynchronously, it will be faster to do it inline, so test to see if > + * our CPU can do hardware crc32c and if it can just do the csum in our > + * threads context. > + */ > +#ifdef CONFIG_X86 > + if (cpu_has_xmm4_2) { > + printk(KERN_ERR "doing it the fast way\n"); You'll probably go to hell for the printk... > + ret = btree_csum_one_bio(bio); > + if (ret) > + return ret; > + return btrfs_map_bio(BTRFS_I(inode)->root, rw, bio, mirror_num, 0); > + } > +#endif > + /* > * kthread helpers are used to submit writes so that checksumming > * can happen in parallel across all CPUs > */ >