[poppler] Migrating poppler to liblcms2 from liblcms1

Sun Jan 29 15:03:13 PST 2012

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. 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