Re: VBO not faster than immediate mode?

Subject: Re: VBO not faster than immediate mode?

Date: Sun, 25 May 2008 17:50:38 +0300

Delivered-to: email@hidden

Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:message-id:from:to:in-reply-to:content-type:mime-version:subject:date:references:x-mailer; bh=VIMo5WszT9wHux2tEu9kqVAHaZHcFVpyqdqcidD7S1Y=; b=n08WHU+5GPPpImgxykwzeqa8n5Z3m5N1h2eqfT+SlioJuyDc2KNBqKJF/UEzadn4nXufSCgkQ2m/PM6xNpFo4tklyx/N+WtNWNR2C+rsG+F9RwvsVeji4C+Tkv29Lg3trrgY4OLdCG0BIkOtlb/tgrRdjvk45ugNCFgtbtDgAMs=

Domainkey-signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:from:to:in-reply-to:content-type:mime-version:subject:date:references:x-mailer; b=dgZ/f0RIc0x2IW8hz2/5eBpQBbeFGSj8e5GqW1hcczKUAY+eRMsMAxYtm+FIQ9cypBi2o1v5PTzRHEjExjpi5eAXoviGxT1gMzu6egWZjFWqen7HSxiEzpyP1dJ9eW+DtUKK/5Zyb7Dw5cJnB95sLbJonvW+7ZabQvlw3CWZGP4=

Thanks Ben,

Like I mentioned I have never used shark (just recently switched to Mac in the first place so EVERYTHING is new to me - even OpenGL).

I tried Time Profile (All Thread States) and the results are quite different:

31.0% 31.0% libSystem.B.dylib __semwait_signal

0.0% 31.0% libSystem.B.dylib _pthread_cond_wait

0.0% 31.0% libSystem.B.dylib pthread_cond_wait$UNIX2003

0.0% 15.5% libGLProgrammability.dylib glvmDoWork

0.0% 15.5% libSystem.B.dylib _pthread_start

0.0% 15.5% libSystem.B.dylib thread_start

0.0% 15.5% QuartzCore fe_fragment_thread

0.0% 15.5% libSystem.B.dylib _pthread_start

0.0% 15.5% libSystem.B.dylib thread_start

28.3% 28.3% libSystem.B.dylib mach_msg_trap

0.0% 28.3% libSystem.B.dylib mach_msg

0.0% 15.5% OpenGL glcDebugListener

0.0% 7.7% CoreFoundation CFRunLoopRunSpecific

0.0% 2.0% CoreGraphics _CGSGetPortStreamInline

0.0% 1.3% libSystem.B.dylib mach_port_get_set_status

20.4% 20.4% iParticle updateSimulation

11.1% 11.1% libSystem.B.dylib thread_start

2.8% 2.8% libSystem.B.dylib pow$fenv_access_off

2.3% 2.3% libSystem.B.dylib __bsdthread_create

This with VBO's and 200k particles and approx. 45-60 fps.

Well, few things are messy and I am aware of it. I have timer for redraws. After redraw (=update and draw VBO buffers) I simply spawn 4 threads for calculations hoping they finish before next redraw. That was a quick hack but everything seems to work without garbage on screen.

Anyway it seems that I am wasting also 11% for those thread spawnings (which I suspected) so I need to design little better system for those with my limited (read non-existing) threading knowledge.

So what else should I read from the Shark results?

There seems to be whopping 60% of time where something is blocking. Probably both; the VBO update and my kludged threading model?

-mike

Ben Supnik kirjoitti 25.5.2008 kello 16:24:

Hi Mike,

Depends on which profile you used...if you are CPU limited and that is "time profile" then yes, becaue it's telling you where CPU is going.

But often with VBOs the bottleneck is in wait time....the timed profiler only counts functions when they do work, not when they block. But blocking slows down your fps.

Try "time profile (all states)" - that shows time spent in the function both working AND blocking....

Time profile can spot possible speed-ups by improving the speed of code.

Time profile (all states) can spot possible speed-ups by removing blocking.

cheers
Ben

_______________________________________________ Do not post admin requests to the list. They will be ignored. Mac-opengl mailing list (email@hidden) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/mac-opengl/email@hidden This email sent to email@hidden

References:
	>VBO not faster than immediate mode? (From: Mike <email@hidden>)
	>Re: VBO not faster than immediate mode? (From: "Bob Free" <email@hidden>)
	>Re: VBO not faster than immediate mode? (From: Mike <email@hidden>)