linux-kernel - Re: [linux-pm] [PATCH 0/8] Suspend block api (version 8)

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20100604150901.50a115e1@schatten.dmk.lab>
Date:	Fri, 4 Jun 2010 15:09:01 +0200
From:	Florian Mickler <florian@...kler.org>
To:	Arve Hjønnevåg <arve@...roid.com>
Cc:	"Rafael J. Wysocki" <rjw@...k.pl>,
	James Bottomley <James.Bottomley@...e.de>,
	markgross@...gnar.org, 640e9920@...il.com,
	Peter Zijlstra <peterz@...radead.org>,
	Brian Swetland <swetland@...gle.com>,
	Ingo Molnar <mingo@...e.hu>,
	LKML <linux-kernel@...r.kernel.org>,
	Linux PM <linux-pm@...ts.linux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Alan Cox <alan@...rguk.ukuu.org.uk>
Subject: Re: [linux-pm] [PATCH 0/8] Suspend block api (version 8)

On Thu, 3 Jun 2010 21:07:07 -0700
Arve Hjønnevåg <arve@...roid.com> wrote:

> On Thu, Jun 3, 2010 at 2:05 PM, Rafael J. Wysocki <rjw@...k.pl> wrote:
> > On Thursday 03 June 2010, James Bottomley wrote:
> >> On Thu, 2010-06-03 at 00:10 -0700, Arve Hjønnevåg wrote:
> >> > A request update then becomes something like this:
> >> >   if on primary list {
> >> >     unlink from primary list
> >> >     if secondary list is not empty
> >> >       get next secondary entry and add in same spot on primary list
> >> >   }
> >> >   unlink from secondary list
> >> >   find new spot on primary list
> >> >   if already there
> >> >     add to secondary list
> >> >   else
> >> >     add to primary list
> >>
> >> This is just reinventing hash bucketed lists.  To get the benefits, all
> >> we do is implement an N state constraint as backed by an N bucketed hash
> >> list, which the kernel already has all the internal mechanics for.
> >
> > Agreed.
> >
> 
> No, a hash is used for quick lookup of a specific value, not to find
> an extreme value. It is however extremely similar to plists. The only
> difference is that plists link all the secondary lists together. If we
> want to have constraints that autoexpire, then keeping the secondary
> lists separate allows the same optimization as I did for
> wakelock/suspend_blocker timeouts where no timer is active if an
> (equal or stricter) non-expiring constraint is active.

Can you give an example for the optimization or elaborate about the
negative effect of linking the secondary lists together? I don't
understand right now.

Would be hlist from list.h better? (I think that is what James is
referring to?) That is a (single-linked-)list of double-linked-lists. 

Cheers,
Flo
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/