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Alphonso



Joined: 16 Jan 2007
Posts: 294
Alphonso
Why do so many people think this is a bad idea? Sure, it would be nice to have some finer control but would it not be able to provide some improvement with executables?
Post 08 Sep 2012, 07:19
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f0dder



Joined: 19 Feb 2004
Posts: 3170
Location: Denmark
f0dder
Alphonso wrote:
Why do so many people think this is a bad idea? Sure, it would be nice to have some finer control but would it not be able to provide some improvement with executables?
Because people are stupid Smile

Sure, SSDs are fast, but RAM is still a lot faster.

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Post 08 Sep 2012, 11:08
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Alphonso



Joined: 16 Jan 2007
Posts: 294
Alphonso
The reason I ask is because SSD's are fastest with sequential data. An executable with lots of random jumps and the windows mechanism of page faults for each 4k page means random 4k access and that is quite a bit slower. If the executable is prefetched sequentially then the 4k random access can be eliminated.

Of course once the program is loaded there is a good chance that some or all of those pages remain cached in RAM so the next time it is executed is a lot quicker and even quicker still for the parts that remain in the CPU cache.
Post 12 Sep 2012, 06:02
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revolution
When all else fails, read the source


Joined: 24 Aug 2004
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revolution
Alphonso wrote:
The reason I ask is because SSD's are fastest with sequential data.
Question Erm, are you thinking of HDDs being terrible at random access patterns? SSDs are solid state so don't have to move heads, or wait for a rotation, to find the next sector.
Post 12 Sep 2012, 06:09
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Alphonso



Joined: 16 Jan 2007
Posts: 294
Alphonso
No, although HDD'd are worse. Give me a moment and I'll see if I can post an example.
Post 12 Sep 2012, 06:21
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f0dder



Joined: 19 Feb 2004
Posts: 3170
Location: Denmark
f0dder
revolution wrote:
Alphonso wrote:
The reason I ask is because SSD's are fastest with sequential data.
Question Erm, are you thinking of HDDs being terrible at random access patterns? SSDs are solid state so don't have to move heads, or wait for a rotation, to find the next sector.
While SSDs are insanely much more efficient at random-I/O than HDDs, they still do take quite a speed hit compared to sequential I/O.

For an Intel-520 120GB, we're talking ~49MB/s for 4k-random vs ~382MB/s for 128k-sequential. (Source: AnandTech).

Just for fun, Intel-5120 120GB benchmarked against VelociRaptor 600GB (one of the faster HDDs available to normal consumers): the HDD is in the zero-dot-something range, while it's able to do ~145MB/s in sequential-128 Smile

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Post 12 Sep 2012, 10:32
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