One more setting!

Story: Tales from responsivenessland: why Linux feels slow, and how to fix thatTotal Replies: 20
Author Content
dinotrac

Oct 04, 2007
7:14 AM EDT
I've been doing the swappiness thing for some time. In fact, I realized that the permanent setting "got lost" on my workstation when it got sooo sloooow.

The vfs_cache_pressure is one that I haven't played with yet...so I'll have to give it a try.
number6x

Oct 04, 2007
7:24 AM EDT
dino,

Do you set it to 1, like in the article?

Or do you use something else?

I usually go with 20, but I run a few database serevrs, lighty and apache on my desktop for development. I have different needs.

I leave real servers at 60, but might try playing with the directory caching on some of the web servers after reading that article.
gus3

Oct 04, 2007
7:51 AM EDT
I wrote a program to test "how much memory can one program malloc()?". When swappiness was set to 0, it would fail almost as soon as the system began thrashing. When swappiness was set to 20, it was more willing to swap before failing.

Complaint about the article: Rudd uses both "echo blah > /proc/sys/vm/something" and "sysctl -w vm.something=blah", sometimes in the same set of "try this" commands. Does he understand they're two ways to do the same thing?
dinotrac

Oct 04, 2007
8:22 AM EDT
I tend to set it to 10, but I haven't done any testing to find the ideal setting.
tracyanne

Oct 04, 2007
1:54 PM EDT
At last something I can play with to get my desktop responsiveness the way I expect.
tracyanne

Oct 04, 2007
11:48 PM EDT
That makes the world of difference.
gus3

Oct 05, 2007
9:43 AM EDT
Adjusting vfs_cache_pressure to 50 slows down my initial cold-cache launches, but the later warm-cache launches are incredibly fast!
Abe

Oct 05, 2007
10:54 AM EDT
Quoting:That makes the world of difference.
Well Tracyanne, do you still think that we need to have two separate releases/forks of the kernel?

What I am hoping for, is one of these days, the kernel or distros developers would create a tuning tool to automatically optimize the kernel parameters to get the best performance of any Linux box. This could be done via a tool that is launched by the user (on a server or desktop) and keeps running for a specified period (like a month). By the end of this period, it makes a logical suggestion to the user based on the statistics it collected, which takes in consideration the hardware resources and application that the users runs to change certain parameters that would improve performance. Running such a tool periodically where the user eventually ends up with best performing machine with the resources available. May be even recommend increase of hardware resources if necessary due to bottle necks.

It has been done on VMS and I am sure it can be done on Linux.



Sander_Marechal

Oct 05, 2007
12:09 PM EDT
Yeah, VMS does have a couple of nice points beneath all the warts.
Abe

Oct 05, 2007
12:16 PM EDT
Quoting:VMS does have a couple of nice points beneath all the warts.
Why are you looking for trouble! You shouldn't have said that, not to me. Now you have to name those warts.

Sander_Marechal

Oct 05, 2007
2:48 PM EDT
"set def". Enough said :-)

I used to manage some VMS machines at my previous job. IIRC they ran an older version of HP's OpenVMS.
Abe

Oct 05, 2007
6:31 PM EDT
Quoting:"set def". Enough said


cd :== "set def" ls :== "dir/date/size +what_ever_qualifiers"

Now you have Linux commands.

If it was HP, then OpenVMS used would be version v7 or v8.

What is great about v8 is it its new file system called Galaxy. It is a Journal File System that has features no other has it. It was designed for speed no matter how large the file system grows. It achieves high performance by creating little file systems dynamically within the Master file system (That is why it is called Galaxy). Those file system gets merged into the galaxy periodically or on demand.

Just imagine a cosmic galaxy with solar systems and planets.

I think that should give an idea about its sophistication and complexity.

I believe that is what MS is trying to do with their new WinFS and failed so far. I bet they will end up buying it form HP or hire all the VMS engineers just like they did when they hired the architect and top 200 VMS engineers who eventually built NT.

Linux is great, but I still think VMS is the best ever created.

tracyanne

Oct 05, 2007
7:52 PM EDT
Quoting:Well Tracyanne, do you still think that we need to have two separate releases/forks of the kernel?


No, but I was never convinced that we did in the first place. I did think that we might need different schedulers, or possibly a scheduler differently tuned for desktop and desktop use.

The cache optimisation doesn't cure all ills, I still see the mouse clearing parts of the splash screens of various applications, but that is I think more to do with a combination of the modularity of the Linux desktop and application threading, where the application isn't repainting it's own window space properly.
gus3

Oct 05, 2007
9:55 PM EDT
rhinoceros : horse :: tank : car :: VMS : Unix :: Windows NT : Mac OS X

http://gus3.typepad.com/i_am_therefore_i_think/2007/09/old-w...
Sander_Marechal

Oct 06, 2007
12:34 AM EDT
Quoting:Now you have Linux commands.


Sorry, SET DEF $SDA1:[ETC.APACHE2] doesn't seem to work for me :-)

Now, I didn't mean to say VMS wasn't very powerful. Just that it's clunky to use.
jezuch

Oct 06, 2007
3:01 AM EDT
Quoting:I still see the mouse clearing parts of the splash screens of various applications,


I thought these days the mouse cursor was handled by the graphics card. I even had situations when X got locked up, but the mouse cursor worked fine (without repainting problems) :)
tracyanne

Oct 06, 2007
4:49 AM EDT
Quoting:I thought these days the mouse cursor was handled by the graphics card. I even had situations when X got locked up, but the mouse cursor worked fine (without repainting problems) :)


I see it happen quite often - I'm using a 1.75 GigHz dual core Pentium (Core Duo) on an Optima Centoris, with Intel i945 graphics card - when launching Mandriva Control centre (drakconf) or K3B, for example. The Mouse cursor - I'm using the bouncing cursor clears parts of the splash screen, in fact i can remove the text "Mandriva Linux Control Centre" before the application window loads. I can do similar things on K3B. The splash screens don't repaint themselves during the application load process. It happens on other applications as well. It doesn't happen on Java applications.
Abe

Oct 06, 2007
10:03 AM EDT
Quoting:Sorry, SET DEF $SDA1:[ETC.APACHE2] doesn't seem to work for me :-)
I take it you don't like the syntax!

You know you can create aliases, logical names, symbolic and hard links similar to Linux!

All of them can be defined in login scripts or defined as variables that can be included in System table, groups tables, users tables and processes tables that are searched in that order. And very fast too.

VMS is indeed very powerful.

gus3

Oct 06, 2007
10:26 AM EDT
VMS is powerful, the way a Sherman tank is powerful. It's good for some jobs, but driving to the store twice a week is not one of them. ;-)
jezuch

Oct 06, 2007
4:09 PM EDT
Quoting:It doesn't happen on Java applications.


You have everything reversed then ;) If something is bemoaned for its laggy repaints, it's Java. Anyway, you could look for "hardware mouse cursor". I don't guarantee that I know what I'm talking about, but that's the phrase that stuck in my memory :)
Abe

Oct 07, 2007
1:39 PM EDT
Quoting:VMS is powerful, the way a Sherman tank is powerful.
True and I agree.

Quoting:but driving to the store twice a week is not one of them. ;-)
That was in the old days when memory was expensive and not as condensed and best CPU still in 500Mhz.

Today we get 1 GB simms for $50 and CPU with speeds up to 3GHz. relatively, VMS hasn't been stagnant either. NT is a miniatured stripped down and modified to run on desktops. You can do the same to VMS but in a much better fashion since it is modular like Linux. VMS has very nice Run Time Libraries (RTL) that are shareable and loadable dynamically. So you can dynamically tailor the systems to your needs. You can even include library routines as static objects into your executable if you chose to when you don't want to use RTLs to avoid incompatibilities/conflicts.

It is not only powerful, it is very tailorable and highly flexible.

Actually, Dave Cutler, architect of both VMS & NT, was heading a group of 200 software engineers. The goal was to create mini-VMS for the MicroVax at that time. Things weren't going that good for Digital due to the Unix competition from Sun and their allocating of resources for the Alpha and its OpenVMS version. Digital had to hold the project and MS grabbed the opportunity and enticed this group to join MS and develop NT.

They succeeded...And the rest is history.

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