[poppler] Migrating poppler to liblcms2 from liblcms1

Sun Jan 29 15:07:19 PST 2012

El Dilluns, 30 de gener de 2012, a les 00:03:13, Albert Astals Cid va 
escriure:
> El Diumenge, 29 de gener de 2012, a les 17:27:43, Maria, Marti va escriure:
> > Great, I would suggest just one test more. Try to convert a PDF with an
> > huge raster image > 400Mb. The xput gain of lcms2 should be evident in
> > this case. Regards.
> 
> I am not denying there will not be an improvement in this case. 

I think i have one too man "not" in there but i hope my message was 
understood.

Albert

> It is just
> that i prefer it to be "as fast" as it was before, not faster in some cases
> and slower in others.
> 
> Albert
> 
> > Marti
> > 
> > -----Original Message-----
> > From: Albert Astals Cid [mailto:tsdgeos at gmail.com] On Behalf Of Albert
> > Astals Cid Sent: sábado, 28 de enero de 2012 16:48
> > To: poppler at lists.freedesktop.org
> > Cc: Maria, Marti; seb128 at ubuntu.com; Till Kamppeter; Koji Otani
> > Subject: Re: [poppler] Migrating poppler to liblcms2 from liblcms1
> > 
> > El Divendres, 27 de gener de 2012, a les 18:23:50, Albert Astals Cid va
> > 
> > escriure:
> > > El Divendres, 27 de gener de 2012, a les 10:39:18, Maria, Marti va
> 
> escriure:
> > > > Bon dia Albert,
> > > 
> > > Hola
> > > 
> > > > That makes a lot of sense. Lcms2 spends more time on optimizing
> > > > the
> > > > transform in order to make it faster. That means create
> > > > transform is
> > > > currently slower that lcms1 but applying transforms  is way
> > > > faster.
> > > > This was indeed a design decision, as most of time creation of
> > > > transforms happens only once at the very beginning and then this
> > > > transform is applied to huge amounts of raster. The performance
> > > > tests I send didn't take creation time into account.
> > > > 
> > > > I will take this action item to review creation time in the next
> > > > release.
> > > > Otherwise, you may consider reusing transforms.
> > > 
> > > We reuse the transforms, it is just that this file has lots of them.
> > > 
> > > > That would speed up both
> > > > lcms1 and lcms2.  If this is not feasible, there is a flags
> > > > cmsFLAGS_NOOPTIMIZE, that makes transform creation fast, at the
> > > > expense of slower dotransfom operation. This is not recommended
> > > > at
> > > > all because you disable all optimizations, but may solve the
> > > > issue
> > > > when creating transforms that are applied only to few bytes.
> > > 
> > > Not sure if i can now to how many bytes it'll be applied but i'll do
> > > some testing and maybe just enable it for the time being so at least
> > > we have the same behaviour than when using lcms1, might not be
> > > faster
> > > but we not slower either.
> > 
> > Using cmsFLAGS_NOOPTIMIZE brings back altona_technical_1v2_x3.pdf to an
> > acceptable speed again.
> > 
> > Koji can you please update your patch so it uses the cmsFLAGS_NOOPTIMIZE
> > when compiling with lmcs2?
> > 
> > Albert
> > 
> > > Thanks,
> > > 
> > >   Albert
> > >   
> > > > Again, thanks for reporting. I'm putting the transform creation
> > > > time
> > > > issue high in my priority list.
> > > > 
> > > > Best regards
> > > > 
> > > > Marti Maria,  Color Engineer
> > > > HP Large Format Printers Division - Barcelona marti.maria at hp.com
> > > > 
> > > > 
> > > > 
> > > > -----Original Message-----
> > > > From: Albert Astals Cid [mailto:tsdgeos at gmail.com] On Behalf Of
> > > > Albert Astals Cid Sent: jueves, 26 de enero de 2012 19:43
> > > > To: poppler at lists.freedesktop.org
> > > > Cc: Maria, Marti; Till Kamppeter; seb128 at ubuntu.com
> > > > Subject: Re: [poppler] Migrating poppler to liblcms2 from
> > > > liblcms1
> > > > 
> > > > El Dilluns, 23 de gener de 2012, a les 11:16:03, Maria, Marti va
> 
> escriure:
> > > > > Hi,
> > > > > In my testings lcms2 is significantly faster that lcms1
> > > > > except
> > > > > when using floating point, then lcms2 favors precision.
> > > > 
> > > > Is this precision is so important to justify a 10x slowliness?
> > > > Maybe
> > > > it'd be a good idea to have a fallback fast mode for those not
> > > > willing to take that 10x hit?
> > > > 
> > > > > http://littlecms2.blogspot.com/2010/03/xput-comparative-119-
> > > > > vs-2
> > > > > 0.
> > > > > ht
> > > > > ml
> > > > > 
> > > > > Altona test does many different color conversions it would
> > > > > be
> > > > > interesting to know which transformation is going slow.
> > > > 
> > > > Attached the callgrind output of running poppler there, you can
> > > > see
> > > > the time is almost totally spent on creating the transforms.
> > > > 
> > > > Wild guess: I'm wondering if the thing is that not
> > > > transformations
> > > > are all precalculated (meaning a faster overall if you do lots
> > > > of
> > > > access) and previously they were done each time and thus if we
> > > > end
> > > > up doing "few" transformations it was just much faster?
> > > > 
> > > > Cheers,
> > > > 
> > > >   Albert
> > > >   
> > > > > Regards
> > > > > Marti
> > > > > 
> > > > > ________________________________________
> > > > > From: Till Kamppeter [till.kamppeter at gmail.com]
> > > > > Sent: Monday, January 23, 2012 8:58 AM
> > > > > To: Albert Astals Cid
> > > > > Cc: poppler at lists.freedesktop.org; Maria, Marti; Sebastien
> > > > > Bacher;
> > > > > Koji Otani Subject: Re: [poppler] Migrating poppler to
> > > > > liblcms2
> > > > > from
> > > > > 
> > > > > liblcms1 On 01/22/2012 11:18 PM, Albert Astals Cid wrote:
> > > > > > Same thing, altona_technical_1v2_x3.pdf still goes up
> > > > > > from x
> > > > > > seconds to 10x seconds when going from lcms1 to lcms2.
> > > > > > 
> > > > > > That is in my opinion not acceptable (of course i'm not
> > > > > > ruling
> > > > > > out that we in poppler are using lcms2 wrong). Till,
> > > > > > does
> > > > > > your
> > > > > > ubuntu work cover fixing the regressions of moving from
> > > > > > lcms1 to
> > > > > > lcms2 or all your work covers is making stuff compile?
> > > > > 
> > > > > I downloaded altona_technical_1v2_x3.pdf from
> > > > > http://www.eci.org/doku.php?id=es:downloads and tried
> > > > > pdftops on
> > > > > Ubuntu Oneiric (11.10, lcms1) and on Precise (12.04, lcms2,
> > > > > Koji
> > > > > Otani's patch) and with lcms1 it takes 3.5 seconds and with
> > > > > lcms2
> > > > > 17.5
> > > > > seconds.
> > > > > 
> > > > > The same problem occurs with Ghostscript: There the same
> > > > > transition happened from Oneiric to Precise and here Oneiric
> > > > > is
> > > > > much faster with this file, too. In Precise PDF rendering
> > > > > for
> > > > > printing is done by Ghostscript and not by Poppler, so lcms2
> > > > > is
> > > > > already used for printing in Precise for some time. As there
> > > > > are
> > > > > no performance complaints by users yet, it seems that for
> > > > > everyday
> > > > > files there is not such a significant performance loss. and
> > > > > this
> > > > > 
> > > > > Marti, can you check what is the problem with lcms2 and this
> > > > > PDF
> > > > > file and also why most files are somewhat slower with lcms2?
> > > > > 
> > > > >     Till
> > > > > 
> > > > > _______________________________________________
> > > > > poppler mailing list
> > > > > poppler at lists.freedesktop.org
> > > > > http://lists.freedesktop.org/mailman/listinfo/poppler
> > > 
> > > _______________________________________________
> > > poppler mailing list
> > > poppler at lists.freedesktop.org
> > > http://lists.freedesktop.org/mailman/listinfo/poppler
> 
> _______________________________________________
> poppler mailing list
> poppler at lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/poppler