Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764914AbXHQQXY (ORCPT ); Fri, 17 Aug 2007 12:23:24 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751120AbXHQQXO (ORCPT ); Fri, 17 Aug 2007 12:23:14 -0400 Received: from viefep18-int.chello.at ([213.46.255.22]:10113 "EHLO viefep34-int.chello.at" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754613AbXHQQXM (ORCPT ); Fri, 17 Aug 2007 12:23:12 -0400 Subject: Re: [PATCH 16/23] mm: scalable bdi statistics counters. From: Peter Zijlstra To: Josef Sipek Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, miklos@szeredi.hu, akpm@linux-foundation.org, neilb@suse.de, dgc@sgi.com, tomoki.sekiyama.qu@hitachi.com, nikita@clusterfs.com, trond.myklebust@fys.uio.no, yingchao.zhou@gmail.com, richard@rsk.demon.co.uk, torvalds@linux-foundation.org In-Reply-To: <20070817162030.GA27836@filer.fsl.cs.sunysb.edu> References: <20070816074525.065850000@chello.nl> <20070816074628.520798000@chello.nl> <20070817162030.GA27836@filer.fsl.cs.sunysb.edu> Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=-HE5+SSmnle+pT2IB5ITF" Date: Fri, 17 Aug 2007 18:23:02 +0200 Message-Id: <1187367782.6114.132.camel@twins> Mime-Version: 1.0 X-Mailer: Evolution 2.10.1 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2620 Lines: 82 --=-HE5+SSmnle+pT2IB5ITF Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On Fri, 2007-08-17 at 12:20 -0400, Josef Sipek wrote: > On Thu, Aug 16, 2007 at 09:45:41AM +0200, Peter Zijlstra wrote: > .... > > Index: linux-2.6/include/linux/backing-dev.h > > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > > --- linux-2.6.orig/include/linux/backing-dev.h > > +++ linux-2.6/include/linux/backing-dev.h > .... > > @@ -24,6 +26,12 @@ enum bdi_state { > > =20 > > typedef int (congested_fn)(void *, int); > > =20 > > +enum bdi_stat_item { > > + NR_BDI_STAT_ITEMS > > +}; >=20 > enum numbering starts at 0, so NR_BDI_STAT_ITEMS =3D=3D 0 >=20 > > + > > +#define BDI_STAT_BATCH (8*(1+ilog2(nr_cpu_ids))) > > + > > struct backing_dev_info { > > unsigned long ra_pages; /* max readahead in PAGE_CACHE_SIZE units */ > > unsigned long state; /* Always use atomic bitops on this */ > > @@ -32,15 +40,86 @@ struct backing_dev_info { > > void *congested_data; /* Pointer to aux data for congested func */ > > void (*unplug_io_fn)(struct backing_dev_info *, struct page *); > > void *unplug_io_data; > > + > > + struct percpu_counter bdi_stat[NR_BDI_STAT_ITEMS]; >=20 > So, this is a 0-element array. >=20 > > }; > > =20 > > -static inline int bdi_init(struct backing_dev_info *bdi) > > +int bdi_init(struct backing_dev_info *bdi); > > +void bdi_destroy(struct backing_dev_info *bdi); > > + > > +static inline void __add_bdi_stat(struct backing_dev_info *bdi, > > + enum bdi_stat_item item, s64 amount) > > { > > - return 0; > > + __percpu_counter_add(&bdi->bdi_stat[item], amount, BDI_STAT_BATCH); >=20 > Boom! >=20 > > } Quite so, but since there are no callers _yet_ it will not go boom :-) This patch introduces the framework, patch 17 and 18 will introduce both stat items and callers. So it should all work out just fine. --=-HE5+SSmnle+pT2IB5ITF Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) iD8DBQBGxctmXA2jU0ANEf4RAonUAJ4iD7JBaQB2UgldCQniZdBibJwbpgCgiwcQ q9JNa142MkTqspID2JJEZgM= =WwQO -----END PGP SIGNATURE----- --=-HE5+SSmnle+pT2IB5ITF-- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/