Write Allocation

Discuss software and how to tweak more performance out of your system.
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Newbie K6'er
Posts: 20
Joined: Fri Aug 10, 2001 7:23 am

Write Allocation

Post by DrBob » Fri Nov 09, 2001 2:06 pm

I getting used to my new K6-III+ Processor and have learned that programs like SysID and K6Speed allow one to enable and set write allocation.<br><br>What is "write allocation"?<br><br>What is an optimum setting? <br><br>Finally, what is "speculative write combining" ? <br><br>Thanks! <p></p><i></i>

Newbie K6'er
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Joined: Mon Jun 11, 2001 11:27 am

Re: Write Allocation

Post by RobM » Sun Nov 11, 2001 4:36 pm

<!--EZCODE QUOTE START--><blockquote><b><i>Quote:</i></b><hr> What is "write allocation"?<hr></blockquote><!--EZCODE QUOTE END--><br>Short answer: "Read before write".<br>Long answer: <br>If the destination of a write to cacheable memory is not in L1 cache or in L2 cache (if the CPU has on-die L2 cache) the CPU first reads an entire cache line into L1/L2 cache. Writing to the L1/L2 cache is much faster than writing to main memory. Since it is very likely that a future write will be to this particular cache line this boosts performance. <br>With random memory writes this hurts performance since many useless cache lines are being read.<br><!--EZCODE QUOTE START--><blockquote><b><i>Quote:</i></b><hr> What is an optimum setting?<hr></blockquote><!--EZCODE QUOTE END--><br>The amount of RAM you have in your system.<br><!--EZCODE QUOTE START--><blockquote><b><i>Quote:</i></b><hr> Finally, what is "speculative write combining" ?<hr></blockquote><!--EZCODE QUOTE END--><br>I think this is not used with any existing socket7 mobo. <p></p><i></i>


CTU setting for write ordering

Post by mike » Thu Nov 04, 2004 9:09 pm

I'd like to ask how to disable write ordering in CTU. What is the correct CTU setting for this? Also, does write allocation help performance?


Post by DasMan2 » Fri Nov 05, 2004 11:43 am

Mike , in CTU program write ordering is easily turned off by chosing the "No Write ordering" selection at the bottom of the display panel where there are 3 choices .

To assure that your choice is retained to be always run that way you have to hit "apply" then unclick the check box just above it (to clear out old settings) and to retain the new changes. then you have to hit "Apply" again which will clear the check box just above once again.

Now hit the check box to have a check mark in there again ,then hit "Apply" one last time which should pop up a Info display window stating that Central Tweaking Unit will apply it also for the next restart.
This way you have confirmation it has indeed been Applied /retained/ and activated.

This procedure will confirm any settings chosen are retained for automatic running next time around permanently ...until you change it or sometimes if you replace memory or a video card CTU responds to that swap and goes into default or somethings can be changed in your display that you have to re-do.

Your BIOS may have that selection that may need turning off 1st , not sure there.

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