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Date:      Mon, 14 May 2012 14:13:50 +0300
From:      Konstantin Belousov <kostikbel@gmail.com>
To:        Grzegorz Bernacki <gber@freebsd.org>
Cc:        svn-src-projects@freebsd.org, src-committers@freebsd.org, Mateusz Guzik <mjg@semihalf.com>
Subject:   Re: svn commit: r233072 - projects/nand/sys/kern
Message-ID:  <20120514111350.GF2358@deviant.kiev.zoral.com.ua>
In-Reply-To: <4FB10305.5020002@freebsd.org>
References:  <4FA8FFB9.7090002@freebsd.org> <20120508095631.GV2358@deviant.kiev.zoral.com.ua> <4FA94609.3060306@freebsd.org> <20120510103105.GG2358@deviant.kiev.zoral.com.ua> <4FABC64F.3060502@freebsd.org> <20120510115857.GH2358@deviant.kiev.zoral.com.ua> <20120510164519.GA13258@pcbsd-2342.semihalf.com> <20120511104648.GM2358@deviant.kiev.zoral.com.ua> <20120511154810.GA99005@pcbsd-2342.semihalf.com> <4FB10305.5020002@freebsd.org>

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On Mon, May 14, 2012 at 03:05:09PM +0200, Grzegorz Bernacki wrote:
> On 05/11/12 17:48, Mateusz Guzik wrote:
> >On Fri, May 11, 2012 at 01:46:48PM +0300, Konstantin Belousov wrote:
> >>On Thu, May 10, 2012 at 06:45:19PM +0200, Mateusz Guzik wrote:
> >>>http://people.freebsd.org/~raj/patches/misc/vfs_highdirtybuf.diff
> >>>
> >>>callbacks are expected to increase flushed counter if they happend to
> >>>flush some buffers.
> >>I do not think this is right. You need to call a routine when getnewblk=
()
> >>is unable to find a buffer to recycle.
> >>
> >>As I understand, in your situation with lot of managed buffers, the dir=
ty
> >>queue could be just empty.
> >
> >I don't think I follow. Is your concern that with a lot of managed buffe=
rs=20
> >and
> >empty dirty queue nothing can be recycled? Or that managed buffers
> >affect calls to buf_do_flush?
> >
> >I presume you talk about the code below the following:
> >         /*
> >          * If we exhausted our list, sleep as appropriate.  We may have=
 to
> >          * wakeup various daemons and write out some dirty buffers.
> >          *
> >          * Generally we are sleeping due to insufficient buffer space.
> >          */
> >
> >         if (bp =3D=3D NULL) {
> >
> >Conditions that cause bufdaemon weakups/buf_do_flush calls seem to be
> >not dependent on buffers being managed or not.
> >
> >buf_do_flush with our change always calls registered callbacks and the
> >callback that we register calls code that knowns what nandfs managed
> >buffers are dirty and flushes those. Buffers from dirty queues (if any)
> >are flushed separately.
> >
> >If I'm wrong or misunderstood you, please elaborate on problem you have
> >in mind.
> >
> >>>
> >>>Example proof-of-concept (will be cleaned up) change for nandfs:
> >>>http://people.freebsd.org/~raj/patches/misc/nandfs_vfs_highdirtybuf.di=
ff
> >>>
> >>>Does this look reasonable?
> >>>
> >
>=20
>=20
> Hi Kostik,
>=20
> We would like to merge our code into HEAD. Please let us know if you=20
> have any objection. We are still going to work on buf deamon changes,=20
> but we would like to avoid delay on pushing our changes into HEAD.
>=20
> As I understand we agreed that we can merge B_MANAGED change from:
> http://people.freebsd.org/~gber/patches/vfs_bio2.diff

Yes, I have no objections against vfs_bio2.diff.

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