From mboxrd@z Thu Jan 1 00:00:00 1970 From: NeilBrown Subject: Re: [PATCH] md/raid456:Remove the judgement atomic_read(&rdev->read_errors). Date: Thu, 24 May 2012 09:40:22 +1000 Message-ID: <20120524094022.5a951c91@notabene.brown> References: <201205232038121562929@gmail.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=PGP-SHA1; boundary="Sig_/oy0P43lXQ8BlOYql_e+dtu6"; protocol="application/pgp-signature" Return-path: In-Reply-To: <201205232038121562929@gmail.com> Sender: linux-raid-owner@vger.kernel.org To: majianpeng Cc: linux-raid List-Id: linux-raid.ids --Sig_/oy0P43lXQ8BlOYql_e+dtu6 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable On Wed, 23 May 2012 20:38:16 +0800 "majianpeng" wrot= e: > It isn't necessary to judge.Because the atomic_read and atomic_set is exc= uce same cpu. So > read_errors is zero or not, directly set it zero. 'read' imposes less bus contention than 'write'. And read_errors will most often be 0. So if we can avoid lots of unnecessary writes we should. i.e. code is correct as it is. Thanks, NeilBrown > Signed-off-by: majianpeng > --- > drivers/md/raid5.c | 3 +-- > 1 files changed, 1 insertions(+), 2 deletions(-) >=20 > diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c > index f351422..1fe2def 100644 > --- a/drivers/md/raid5.c > +++ b/drivers/md/raid5.c > @@ -1690,8 +1690,7 @@ static void raid5_end_read_request(struct bio * bi,= int error) > clear_bit(R5_ReadError, &sh->dev[i].flags); > clear_bit(R5_ReWrite, &sh->dev[i].flags); > } > - if (atomic_read(&rdev->read_errors)) > - atomic_set(&rdev->read_errors, 0); > + atomic_set(&rdev->read_errors, 0); > } else { > const char *bdn =3D bdevname(rdev->bdev, b); > int retry =3D 0; --Sig_/oy0P43lXQ8BlOYql_e+dtu6 Content-Type: application/pgp-signature; name=signature.asc Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.18 (GNU/Linux) iQIVAwUBT711Zjnsnt1WYoG5AQKw2g//R12LCGozmSUUYLWLNqrxAomJ1pHkNi+x SbKyERk/37MTA9+GUl0fTvq6V+SkebwZMRv8jZA0K0WUWcfwIfGzanuax2UTpF0h qRGejaJEsZgxMmuMwg7vSKoK9WvdOokLSXj3MG3i5WDWWIFz5hwFejBUF8gZSNNA j1bVURkBNjPvu8Z9nAWwGNLQmrsF5o300MmShr/r9/byd/woAQCT9HbB1x2TGn75 pUHVWwaosPwPDn8wwogrDnrlnMn4lSAIex4nkOvDFx8p/+XhWgfXo/GshL8gywLF AKeMJGjPNvzzBOR6nMuH7hfN3/mxIEQaEU35QopQrPuW6klCunS8ra5n/44QdVoM MLxpfSa99dR0gORGJKNmcJyserf8JFjkkL/MNE6mnTeGFc1LWymleSNl4LOxXfxT 40UPT7ZyafcDdInhd6igt5mT6lWFzzN+/rCM0KrSYrDDAM2q9pll7SbaoP8XmsB1 UXTK4kk5mVMwMG9ZEY1nPaELybYFPccOiugKQz/Nt/O/nJuU+kMfQQss1uJOH0vx G46XqGt7JLnson25flA2bXnAR+D+4+xoRC3gH746df2BuVWFH279UHObSNk+2En5 OXRmWWgwbwiQ6+uJeS4RDwUtbxipVXF67DRCMO8NEwqGMexZcrUfJBfWO5X+DAQ7 o+JtL1eVC/g= =muJ4 -----END PGP SIGNATURE----- --Sig_/oy0P43lXQ8BlOYql_e+dtu6--