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Windows XP Myths

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Mastertech:
Try doing disk-cache intensive stuff in a large-memory system and you'll see what I mean. The Microsoft cautions in the knowledge-base article you refer to apply to low-memory systems. The default windows 2k/xp memory management settings might have been fitting for ~128meg machines, but are a bit conservative for modern machines.

Do keep in mind that the filesystem cache is dynamic, and will thus be adjusted depending on full system needs. LargeSystemCache simply means than, on a large-memory machine, your RAM won't be wasted.
--- End quote ---
The knowledgebase article makes no mention of less than 128 MB machines and specifically states the following:

System cache mode is designed for use with Windows server products that act as servers. System cache mode is also designed for limited use with Windows XP, when you use Windows XP as a file server. This mode is not designed for everyday desktop use. If you use a server product as a desktop, you should consider changing the resource allocation to Programs mode or adding more physical RAM.

When you enable System cache mode on a computer that uses Unified Memory Architecture (UMA)-based video hardware or an Accelerated Graphics Port (AGP), you may experience a severe and random decrease in performance. For example, this decrease in performance can include very slow system performance, stop errors, an inability to start the computer, devices or applications that do not load, and system instability.

The drivers for these components consume a large part of the remaining application memory when they are initialized during startup. Also, in this scenario, the system may have insufficient RAM when the following conditions occur:
•   Other drivers and desktop user services request additional resources.
•   Desktop users transfer large files.
--- End quote ---

This is repeated over again in other articles with no mention to the amount of RAM in the system but rather the usage of the machine. If the machine is not being used as a file server you should NOT enable this.

http://technet2.microsoft.com/WindowsServer/en/library/efa621bd-a031-4461-9e72-59197a7507b61033.mspx?mfr=true
Increasing the size of the file system cache generally improves server performance, but it reduces the physical memory space available to applications and services. Similarly, writing system data less frequently minimizes use of the disk subsystem, but the changed pages occupy memory that might otherwise be used by applications.

0 = Establishes a standard size file-system cache of approximately 8 MB. The system allows changed pages to remain in physical memory until the number of available pages drops to approximately 1,000. This setting is recommended for servers running applications that do their own memory caching, such as Microsoft SQL Server, and for applications that perform best with ample memory, such as Internet Information Services (IIS).

1 = Establishes a large system cache working set that can expand to physical memory, minus 4 MB, if needed. The system allows changed pages to remain in physical memory until the number of available pages drops to approximately 250. This setting is recommended for most computers running Windows Server 2003 on large networks.
--- End quote ---

I'm sorry but I believe Microsoft knows what they are talking about in relation to their Operating Systems. If this setting only related to the amount of available RAM than that would clearly be mentioned. If this setting improved application performance than Microsoft would not only be recommending it but have it enabled. >128 MB systems were nothing knew when XP was released.

f0dder:
Microsoft target their knowledgebase articles at the general masses and the general needs. Now let me quote myself, this time with a bit of emphasis:
This tweak can be nice on Desktop machines, not just servers, depending on the way you use your system.
-f0dder (July 19, 2006, 02:14 PM)
--- End quote ---

I've got a lot of memory in this system (2 gigabytes) and I regularly do lots of file operations. LargeSystemCache=1 is a noticable improvement for me, even though this is a desktop machine and not a server. At the same time it doesn't have negative impact, since the FS cache is dynamically adjusted when apps need more memory.

Do take a look at "Inside Windows" and the sysinternals tools if you want to be able to talk about topics like this.

nudone:
f0dder, i've got 2 gig of ram. i use photoshop, acdsee, illustrator, maybe dreamweaver now - all at the same time. do you think i'd benefit from doing the 'largesystemcache=1'?

i also do a fair bit of messing about with video, i.e. editing with premiere and virtualdub encoding - could they benefit from the above question also?

thanks.

f0dder:
nudone: probably not for most of the stuff; the settings tell windows it's okay to use just about much RAM as it wants for filesystem cache, and cache more aggressively. This is mainly useful if you shuffle a lot of file data, and if you need the data more than once.

Think software development, where header files and libraries are used again and again. Or messing with nLite setups and testing in vmware, where the resulting .iso file can often remain cached during install.

There might be some advantage when doing premiere editing, but it depends on how much memory premiere wants to gobble up for itself...

While you might not gain an improvement, you shouldn't see a penalty for the setting - there are situations where it could happen though, like if an application restricts it's memory use based on the currently physically available amount of RAM.

And then there's the warning that you should never enable the setting if you use an ATI card, since their drivers sucks (I wouldn't be surprised if ATI is the sole reason for the BSOD warning in the Microsoft knowledgebase article).
 
Might be worth a try for you.

nudone:
thanks for the advice.

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