About IDE prefetch

eLPuSHeR · 12th Feb 2006, 01:18 AM

I think this setting speeds up sequential read/write by caching subsequent data before being requested (some sort of read-ahead buffer) using the physical hard-drive cache space, but it has a drawback too.

I think it steals IDE cache space to do its work (just like System Bios Cacheable will steal some precious Processor L2 cache size). For my Seagate drive, which isn't a newer model and it just has a limited 2MB cache, drive goes crazy doing what seems to be some frentic buffer flushes every now and them. I have specially noticed this nasty, stuttering behaviour when playing some hardware intensive games (or any application that would need a lot of disk swapping).

So in my experience, I would advise testing this on your particular setup. It may be good for your hard-drive or not. It's up to you to decide.

Have a nice day.

EDIT: Disregard the previous assumption of buffer flushing. I have disabled that option and it's still doing it. Must be something else, then. On the other hand, I would like someone would confirm whether IDE Prefetch takes away some portion of IDE cache memory or not.

Adrian Wong · 14th Feb 2006, 01:30 AM

It has nothing to with the hard drive. It controls the IDE controller's prefetch buffers.

But I thought I covered in the BIOS Optimization Guide?

eLPuSHeR · 14th Feb 2006, 06:10 PM

But IDE controller is located in the drive itself, isn't it?

So, do you mean IDE drives have some sort of buffer for prefetching? (and it has nothing to do with the drive physical cache). Or do you mean the IDE controller located in the mainboard chipset?

I am guessing you mean the latter. So the mainboard must have some sort of buffer for IDE controller. I wasn't aware of that. So, no hurt in enabling that IDE prefetch feature. My HD is rarely fragmented.

Thanks in advance, Adrian.

Adrian Wong · 19th Feb 2006, 02:18 AM

Quote:

Originally Posted by eLPuSHeR

But IDE controller is located in the drive itself, isn't it?

So, do you mean IDE drives have some sort of buffer for prefetching? (and it has nothing to do with the drive physical cache). Or do you mean the IDE controller located in the mainboard chipset?

I am guessing you mean the latter. So the mainboard must have some sort of buffer for IDE controller. I wasn't aware of that. So, no hurt in enabling that IDE prefetch feature. My HD is rarely fragmented.

Thanks in advance, Adrian.

Nope. The IDE controller is part of the motherboard south bridge chip.

No problem.

eLPuSHeR · 19th Feb 2006, 06:22 PM

Thanks for clearing this up Adrian,

Adrian Wong · 25th Feb 2006, 12:38 AM

Quote:

Originally Posted by eLPuSHeR

Thanks for clearing this up Adrian,

No problem.

12th Feb 2006, 01:18 AM	#1 (permalink)
eLPuSHeR Warming up Join Date: 7 Sep 2004 Posts: 89 Reputation: 18 Rep Power: 0	About IDE prefetch I think this setting speeds up sequential read/write by caching subsequent data before being requested (some sort of read-ahead buffer) using the physical hard-drive cache space, but it has a drawback too. I think it steals IDE cache space to do its work (just like System Bios Cacheable will steal some precious Processor L2 cache size). For my Seagate drive, which isn't a newer model and it just has a limited 2MB cache, drive goes crazy doing what seems to be some frentic buffer flushes every now and them. I have specially noticed this nasty, stuttering behaviour when playing some hardware intensive games (or any application that would need a lot of disk swapping). So in my experience, I would advise testing this on your particular setup. It may be good for your hard-drive or not. It's up to you to decide. Have a nice day. EDIT: Disregard the previous assumption of buffer flushing. I have disabled that option and it's still doing it. Must be something else, then. On the other hand, I would like someone would confirm whether IDE Prefetch takes away some portion of IDE cache memory or not. __________________ AMD Sempron 3000+ ABIT NF7 2.0 (nForce2 Ultra 400) 1GB 266Mhz DDR SDRAM WinXP Prof. SP2 ATi Radeon X800GTO AGP (256MB) SoundBlaster Audigy 2 SE Last edited by eLPuSHeR : 12th Feb 2006 at 05:19 PM.

14th Feb 2006, 01:30 AM	#2 (permalink)
Adrian Wong Da Boss Join Date: 10 Oct 2002 Location: In front of my ASUS F8V notebook! Posts: 30,382 Reputation: 3147 Rep Power: 68	It has nothing to with the hard drive. It controls the IDE controller's prefetch buffers. But I thought I covered in the BIOS Optimization Guide? __________________ Dr. Adrian Wong Tech ARP \| Blog @ Tech ARP \| The Free Trade Zone DYKT : The only offshore account I have is at the sand bank? We need PROGRAMMERS and TECHNICAL WRITERS! Contact us if you are a hot shot programmer or technical writer! My items for sale : 50x SD Card \| Memory Stick PRO \| Cyclone Energy Saver \| Seiko SS watch \| Tiger/Carlsberg beer jugs \| Travel Speakers \| Motorola V600 \| Nokia N90 SOLD! \| New Lowepro Mini Trekker AW Other items for sale @ the FTZ : Zalman CNPS9500 LED @ $20 \| Zalman CNPS7700 Cu @ $20 \| Zalman CNPS7000 Cu @ $20 \| Swarovski bracelet watches \| Dell 17" LCD \| Hi-Fi speakers \| English DIVX movies \| HP LaserJet toners! \| Office chairs

14th Feb 2006, 06:10 PM	#3 (permalink)
eLPuSHeR Warming up Join Date: 7 Sep 2004 Posts: 89 Reputation: 18 Rep Power: 0	But IDE controller is located in the drive itself, isn't it? So, do you mean IDE drives have some sort of buffer for prefetching? (and it has nothing to do with the drive physical cache). Or do you mean the IDE controller located in the mainboard chipset? I am guessing you mean the latter. So the mainboard must have some sort of buffer for IDE controller. I wasn't aware of that. So, no hurt in enabling that IDE prefetch feature. My HD is rarely fragmented. Thanks in advance, Adrian. __________________ AMD Sempron 3000+ ABIT NF7 2.0 (nForce2 Ultra 400) 1GB 266Mhz DDR SDRAM WinXP Prof. SP2 ATi Radeon X800GTO AGP (256MB) SoundBlaster Audigy 2 SE

19th Feb 2006, 06:22 PM	#5 (permalink)
eLPuSHeR Warming up Join Date: 7 Sep 2004 Posts: 89 Reputation: 18 Rep Power: 0	Thanks for clearing this up Adrian, __________________ AMD Sempron 3000+ ABIT NF7 2.0 (nForce2 Ultra 400) 1GB 266Mhz DDR SDRAM WinXP Prof. SP2 ATi Radeon X800GTO AGP (256MB) SoundBlaster Audigy 2 SE