From mboxrd@z Thu Jan 1 00:00:00 1970 From: NeilBrown Subject: Re: [PATCH 2/2 V1] raid5: For odirect-write performance, not set STRIPE_PREREAD_ACTIVE. Date: Tue, 17 Jul 2012 12:02:09 +1000 Message-ID: <20120717120209.6b9591ce@notabene.brown> References: <2012071616325740688511@gmail.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=PGP-SHA1; boundary="Sig_/AUpcoV3Nq/_=1l26TgxdctW"; protocol="application/pgp-signature" Return-path: In-Reply-To: <2012071616325740688511@gmail.com> Sender: linux-raid-owner@vger.kernel.org To: majianpeng Cc: linux-raid , viro List-Id: linux-raid.ids --Sig_/AUpcoV3Nq/_=1l26TgxdctW Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable On Mon, 16 Jul 2012 16:33:02 +0800 majianpeng wrote: > Using flag REQ_NOIDLE to difference odirect-write and sync_write. >=20 > Signed-off-by: Jianpeng Ma > --- > drivers/md/raid5.c | 5 ++++- > 1 files changed, 4 insertions(+), 1 deletions(-) >=20 > diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c > index 04348d7..29edaf0 100644 > --- a/drivers/md/raid5.c > +++ b/drivers/md/raid5.c > @@ -4113,7 +4113,10 @@ static void make_request(struct mddev *mddev, stru= ct bio * bi) > finish_wait(&conf->wait_for_overlap, &w); > set_bit(STRIPE_HANDLE, &sh->state); > clear_bit(STRIPE_DELAYED, &sh->state); > - if ((bi->bi_rw & REQ_SYNC) && > + /* Difference odirect-write between regular file > + * and block-device > + */ > + if ((bi->bi_rw & REQ_NOIDLE) && > !test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) > atomic_inc(&conf->preread_active_stripes); > mddev_check_plugged(mddev); Thanks. I've improved that patch description and remove the code comment and I don't think it is helpful. NeilBrown =46rom c6e353648f062901f435f67b91e9438897d42ddf Mon Sep 17 00:00:00 2001 From: majianpeng Date: Tue, 17 Jul 2012 12:00:35 +1000 Subject: [PATCH] md/raid5: For odirect-write performance, do not set STRIPE_PREREAD_ACTIVE. 'sync' writes set both REQ_SYNC and REQ_NOIDLE. O_DIRECT writes set REQ_SYNC but not REQ_NOIDLE. We currently assume that a REQ_SYNC request will not be followed by more requests and so set STRIPE_PREREAD_ACTIVE to expedite the request. This is appropriate for sync requests, but not for O_DIRECT requests. So make the setting of STRIPE_PREREAD_ACTIVE conditional on REQ_NOIDLE rather than REQ_SYNC. This is consistent with the documented meaning of REQ_NOIDLE: __REQ_NOIDLE, /* don't anticipate more IO after this one = */ Signed-off-by: Jianpeng Ma Signed-off-by: NeilBrown diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index 0e4439e..ee492a8 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -4187,7 +4187,7 @@ static void make_request(struct mddev *mddev, struct = bio * bi) finish_wait(&conf->wait_for_overlap, &w); set_bit(STRIPE_HANDLE, &sh->state); clear_bit(STRIPE_DELAYED, &sh->state); - if ((bi->bi_rw & REQ_SYNC) && + if ((bi->bi_rw & REQ_NOIDLE) && !test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) atomic_inc(&conf->preread_active_stripes); release_stripe_plug(mddev, sh); --Sig_/AUpcoV3Nq/_=1l26TgxdctW Content-Type: application/pgp-signature; name=signature.asc Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.18 (GNU/Linux) iQIVAwUBUATHoTnsnt1WYoG5AQIvgBAAnQZ/2CdSwXfsfF1SLz1yCsOH0k9Fe67L Nz1q9MpuDD/UH7bt7ntyUeiXRJM1dM5oOsI26loQsl1OjnO+2zhzYYiuYynnt1bA 9J8GZO92w1cQFM6v1DEbeuLMC44lKW9qvZciL5HGKyCoyQTMC2CiWV9gfpk+pUiQ i1p4Uvubb0WWx4jRAqVKVofIsq9eolJ8oG+jsQSQKCideSyAdgotoZ1e6lKRaylS rGondvR2hGoxWbagYsQa1L+hhu9hBEwjhDMjjRb+VuIluZ72XZJLj6aGZbdivYcC MYUt/MkdlMOdrvu7SAsMS+82e2PleX2MLNzwBPF4FXGHqorWufZE24iv3rDUn1GP vY22y9mKODo1Vd5aBXN39nHcJXpoqmD7H57iSH7VI0TBp0LCniAVsf1dWmTyEFFe rtDkKw/i0+GK8upOtHBZZEXINVAk1nkU8/UZidKr7yxYpx2GJN8fN7Xy39opwKsC hKxagUV7N2jnP8Cg/CRZyRp5VVPZ3fz4hxn4+3IYTHUlshkFUOmaoxwE9gvAgQYo Sf1aYbLRo3uIy60PZpOxDnGbASpppZpgYqmVuxX6GaR8wuZkUVCl+MS0KmdfMO77 9xKtHea+Ff5iuuKGvBGMN818cMlThUaYeI5KQlNfk0cUv/1vKcP7rq2jk4lFfpBZ XfY7oHlm+50= =Ma4G -----END PGP SIGNATURE----- --Sig_/AUpcoV3Nq/_=1l26TgxdctW--