Date: Mon, 14 Apr 2014 21:23:56 +0200 From: Baptiste Daroussin <bapt@freebsd.org> To: Konstantin Belousov <kostikbel@gmail.com> Cc: desrt@desrt.ca, John-Mark Gurney <jmg@funkthat.com>, "freebsd-hackers@freebsd.org" <hackers@freebsd.org> Subject: Re: [CFR] Kevent timer improvements Message-ID: <20140414192356.GB37560@ivaldir.etoilebsd.net> In-Reply-To: <20140414171834.GJ4016@kib.kiev.ua> References: <20140310131632.GI6900@ithaqua.etoilebsd.net> <CAJ-Vmok7ODK7FfJaHiQej8Za4-JH6Aryctk577vM9cYpeUcHew@mail.gmail.com> <20140310180404.GI32089@funkthat.com> <20140413131550.GD17898@ivaldir.etoilebsd.net> <20140413142028.GD4016@kib.kiev.ua> <20140413191928.GE17898@ivaldir.etoilebsd.net> <20140413202038.GE4016@kib.kiev.ua> <20140414061936.GA60058@ivaldir.etoilebsd.net> <20140414171834.GJ4016@kib.kiev.ua>
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--cmJC7u66zC7hs+87 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Apr 14, 2014 at 08:18:34PM +0300, Konstantin Belousov wrote: > On Mon, Apr 14, 2014 at 08:19:37AM +0200, Baptiste Daroussin wrote: > > On Sun, Apr 13, 2014 at 11:20:38PM +0300, Konstantin Belousov wrote: > > > On Sun, Apr 13, 2014 at 09:19:28PM +0200, Baptiste Daroussin wrote: > > > > On Sun, Apr 13, 2014 at 05:20:28PM +0300, Konstantin Belousov wrote: > > > > > On Sun, Apr 13, 2014 at 03:15:51PM +0200, Baptiste Daroussin wrot= e: > > > > > > I have splitted my patch in multiple parts, let start with the = first one: > > > > > > adding NOTE_NSECONDS, NOTE_USECONDS, NOTE_NSECONDS > > > > > >=20 > > > > > > http://people.freebsd.org/~bapt/kevent_timer.diff > > > > >=20 > > > > [...] > > > > > > + else if (flags & NOTE_NSECONDS) > > > > > > + modifier =3D SBT_1NS; > > > > > It is better to put the 'modifier =3D SBT_1MS;' statement as the = else part. > > > > >=20 > > > > > That said, IMO it would be sometimes beneficial to have real flag= to > > > > > specify milliseconds precision, in addition to milliseconds be the > > > > > default. > > > >=20 > > > > Done in the new patch > > > > > > + > > > > > > + timer2sbintime(kn->kn_sdata, kn->kn_sfflags), 0 /* 1ms? = */, > > > > > There, at least the comment about precision should be updated. > > > > > But, it seems that for the seconds precision, it makes sense to > > > > > specify e.g. 1/2 sec as precision; or add an API flag to allow im= precise > > > > > callout scheduling. > > > > >=20 > > > > While I do agree this might be useful I do not have time to work on= that right > > > > now so I just removed the comment which wasn't really accurate anyw= ay. > > > >=20 > > > > Is that ok? > > > Leave XXX comment right near the zero argument, at least ? > > >=20 > > > > + if (flags & NOTE_SECONDS) > > > > + modifier =3D SBT_1S; > > > > + else if (flags & NOTE_USECONDS) > > > > + modifier =3D SBT_1US; > > > > + else if (flags & NOTE_NSECONDS) > > > > + modifier =3D SBT_1NS; > > > > + else > > > > + modifier =3D SBT_1MS; > > > There should be a case for NOTE_MSECONDS. > > >=20 > > ok I'll do > > > Hm, I think the checks should be made stronger. System should ensure > > > that only one flag is passed, and no invalid flags are supplied, righ= t ? > >=20 > > I can check that only one flags is passed and no invalid flagrs are sup= plied but > > from what I see not a single part of kqueue(2) is checking that, so won= 't that > > be inconsistent with the rest of the API? > IMO we should move forward with the better practice. I consider the > current lack of the checks as the deficiency, which hides the application > bugs. >=20 > See the RFTSIGNUM/RFTSIGFLAGS/RFTSIGMASK in unistd.h or > VM_ALLOC_COUNT/VM_ALLOC_COUNT_SHIFT for the idiomatic way to handle > similar needs. I'll do thanks for tips! >=20 > >=20 > > I can probably check that only ona or 0 of the NOTE_*SECONDS is passed = and > > return EINVAL in that case but no more. > >=20 > > (note that more NOTE_* are to be added later) > When added, the checks should be changed. ok I'll come back with a better patch. regards, Bapt --cmJC7u66zC7hs+87 Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iEYEARECAAYFAlNMNcwACgkQ8kTtMUmk6ExLdgCgkKJGiy8YROs6SqBJkguSJY/e 0HwAnjM+WallTnWWchv3WOhfu2IWdI5H =lMPZ -----END PGP SIGNATURE----- --cmJC7u66zC7hs+87--
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