KMountPoint::probablySlow and cifs mount points

[Albert Astals Cid]

El Dilluns, 25 de novembre de 2013, a les 00:01:41, Mark Gaiser va escriure:
> On Sun, Nov 24, 2013 at 10:09 PM, Albert Astals Cid <aacid at kde.org> wrote:
> > El Diumenge, 24 de novembre de 2013, a les 19:42:25, Mark Gaiser va 
escriure:
> >> On Sun, Nov 24, 2013 at 5:05 PM, Albert Astals Cid <aacid at kde.org> wrote:
> >> > In Okular we just got bug
> >> > https://bugs.kde.org/show_bug.cgi?id=327846
> >> > PDF Render time is unreasonably slow over cifs on high latency (WAN)
> >> > network connections
> >> > 
> >> > Basically the issue is that poppler is quite read-intensive over files,
> >> > reading them over and over, and since the file is "local but really
> >> > remote" it takes ages to render for big files.
> >> > 
> >> > The only solution i can think of is doing a local copy and then working
> >> > on
> >> > that.
> >> 
> >> That would work with small files (< 10 MB) but will get you into
> >> trouble for bigger files.
> > 
> > Why?
> 
> See my example below.
> 
> >> You can't - or shouldn't - do that in an automated manner. If the user
> >> manually copies the file and then opens it in a pdf reader: fine. Just
> >> don't auto copy the file. So you can probably give the user a popup
> >> suggesting them to copy the file to his local drive?
> > 
> > Why? If you open a huge file by smb:// it'll copy it to the local file
> > anyway, so why should not we copy it?
> 
> Right. True but should it be like that?
> Lets take playing a movie from smb as an example. If you do that now
> in for example mplayer then kde will simply copy the movie to your
> local drive and start playing it. But should that be the case? I
> consider it a massive usability bug. One that isn't easy to fix. If
> you would mount the same share as cifs then the system "thinks" it's
> local and just plays the movie without copying.
> 
> That is how it should be. Copying to your local system is a nasty
> workaround which should imho be prevented.

A PDF file is not a movie, it can't be read lineraly.

> 
> This is especially a big issue when you want to watch a movie of -
> lets say - 10GB in size. I have that very often and it sucks that it's
> being copied. So i find myself mounting that network drive when i want
> to see something since that is both faster and prevents needless
> copies.
> 
> >> > I saw KMountPoint::probablySlow that says
> >> > 
> >> >     /**
> >> >     
> >> >      * Checks if the filesystem that is probably slow (nfs mounts).
> >> >      * @return true if the filesystem is probably slow
> >> >      */
> >> > 
> >> > And then returns true if the the filesystem type of the mount is nfs,
> >> > autofs or subfs.
> >> > 
> >> > Any objection to replacing
> >> > 
> >> >     /**
> >> >     
> >> >      * Checks if the filesystem that is probably slow (nfs mounts).
> >> >      * @return true if the filesystem is probably slow
> >> >      */
> >> > 
> >> > to
> >> > 
> >> >     /**
> >> >     
> >> >      * Checks if the filesystem that is probably slow (network mounts).
> >> >      * @return true if the filesystem is probably slow
> >> >      */
> >> > 
> >> > and adding cifs to the list of mounttypes that are "probablySlow"?
> >> 
> >> It's not my place to object since the code isn't mine. Yet i do
> >> disagree. Everything becomes slow if you mount it over a WAN. Whatever
> >> it is. It also depends on your internet connection and where you're
> >> connecting to. Saying smb, nfs or cifs is slow - per se - is plain
> >> wrong. All of those are "likely" fast if you mount them locally.
> > 
> > That's why it's called "probablySlow", no?
> 
> It's probably slow if you use a slow connection. It's "probablyFast"
> if you just use it as in internal network. Not over the internet. And
> i think you should assume that most people mount those drives through
> an internal network. The exception is mounting through the internet.
> 
> >> > Or anyone has a better suggestion to fix this issue?
> >> 
> >> What should be done is detecting is the target is mounted via a slow
> >> connection. So if it's mounted via the internet then "probablySlow"
> >> should return true. On the other hand, i don't know if such checks are
> >> in place and if they are not there, how to implement them.
> > 
> > How are you going to define "slow connection"?
> 
> Ping and measure latency? Or use networkmanager to discover if a
> connection is made through a line that is also having the internet
> connection? If so then the connection is made via internet thus
> "probablySlow".
> 
> I don't know if those ideas are possible, but is sounds plausible.

How much is that going to take? is it going to add a 100ms delay to every 
single file you open in Okular so that it can send a few pings and see if they 
come back fast or slow?

Cheers,
  Albert

> 
> > Cheers,
> > 
> >   Albert
> >   
> >> > Cheers,
> >> > 
> >> >   Albert
> >> 
> >> Just my 5 cents.