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Handbrake not maxing out cores in new i7 HTPC

S

soupcxan

Limp Gawd
Joined
Dec 10, 2010
Messages
286
I just built a new HTPC to speed up my bluray encoding times (specs below) so I can have instant access to my movies without getting the disk. While encoding The Avengers bluray last night I noticed that my 8 cores weren't consistently hitting 100% utilization, more like 80% on average with quite a bit of fluctuation. By comparison, the 4 cores in my i5-450M laptop hit 100% solid while encoding the same file on the same settings.

I am not sure if the bottleneck is inherent to splitting encoding across 8 cores, or if there is something else I can fix to get that last 20% of performance out of the system (to encode 20% faster would be huge). My first guess is the hard drive, I haven't put an SSD in it yet, but can encoding at 20 fps really max out a 5400rpm notebook hard drive? Reading a 30GB file in 2 hours is less than 5MB/s so shouldn't be a problem

Is there something else I'm missing?

HTPC:
i7-3770k
Asus P8Z77-M Pro
8GB PC1600
500gb 5400rpm 2.5" hard drive (internal)

Handbrake settings:
~30GB original Avengers MKV
High profile / 1080p / RF:20
 
Are you converting directly from the bluray disk, or from an image on your hard drive? I could see a potential issue arising where your bottleneck is the read speed from the bluray drive, and there's constant read/seek latency--so your CPU cores might be intermittently waiting for that to complete before continuing with the convert process. If you make an image on your hard drive and convert from that and see a higher CPU utilization, that might confirm the issue.
 
I tried moving the encode/decode file on a USB hard drive and vice versa but it made no difference in the encode speed, so don't think it's the hard drive.

I turned off HT on 4 cores using the task manager affinity setting and the utilization dropped to solid 49% whereas with all 8 cores enabled it would average 80% but fluctuate between 70-90% while encoding. So I guess hyperthreading is just not 100% efficient?
 
soupcxan said:
I tried moving the encode/decode file on a USB hard drive and vice versa but it made no difference in the encode speed, so don't think it's the hard drive.

I turned off HT on 4 cores using the task manager affinity setting and the utilization dropped to solid 49% whereas with all 8 cores enabled it would average 80% but fluctuate between 70-90% while encoding. So I guess hyperthreading is just not 100% efficient?
Click to expand...

To my understanding hyperthreading weaves multiple instructions into the 4 physical cores where it can. There just may not be any place to weave in the 4 additional instructions to make the 4 logical cores show as fully utilized.
 
soupcxan said:
I tried moving the encode/decode file on a USB hard drive and vice versa but it made no difference in the encode speed, so don't think it's the hard drive.

I turned off HT on 4 cores using the task manager affinity setting and the utilization dropped to solid 49% whereas with all 8 cores enabled it would average 80% but fluctuate between 70-90% while encoding. So I guess hyperthreading is just not 100% efficient?
Click to expand...


You have a 4 core processor. That answers your question.
 
Older versions of Handbrake exhibited this behavior. The latest version I'm using now fully utilizes my CPU resources. Before I had to start two jobs so I could get 100% utilization.
 
Handbrake's using all the CPU it possibly can. It's just running into resource contention due to the way hyperthreading works.

It's not that it's not using 20% of the CPU; it's that hyperthreading is a cheat to allow it to use 60% more compute resources for free. (Well, not "free". For $100, but without additional silicon.)
 
kac77 said:
Older versions of Handbrake exhibited this behavior. The latest version I'm using now fully utilizes my CPU resources. Before I had to start two jobs so I could get 100% utilization.
Click to expand...

Agreed. I couldn't say what the problem is here, Handbrake does though utilize 95-100% of my 3770K, OC'd at 4.7Ghz and running the same Mobo as the OP.

OP are you running the latest x64 version?
 
its in the setting. I will send you some advance setting that will let you use 100%. I had this same problem. my i7-920 @ 4.2 was not using 100% and I looked for some time and finally figured it out. I will try and get it to you tonight or tomorrow in the am. I have class till 920 pm pacific time.
 
Are you looking at the first pass or the second? Because first pass traditionally tends to not handle multiple cores all that well and largely depends on your settings. the second pass is where it's more likely is used, but it also can be limited by the settings you choose.
 
Turn Decomb off, it'll utilize 100% then. With Blu Ray you shouldn't need Decomb. I'm new to Handbrake myself and when I used default settings I got about 80% utilization as well. With Blu Rays you don't need to de-interlace content so turn it off, and it'll rip faster.
 
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