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#1
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Effective speed of Phenom X3 is faster than Phenom X4 !!
I recently upgraded my AMD Phenom X3 8650 to an X4 9600 with the same
clock speed (2.3GHz). Imagine my surprise when the X4 turned out to be dog slow on my workload, which fundamentally is several (~5) firefox browser with a few hundred tabs to load up. The X4 could not even keep my DSL going at full rate, something which the X3 never had any problem accomplishing. I then switched back to the X3, and everything was much faster again, and the DSL is maxed out. I even tried booting the X4 with the maxcpus=3 (linux, Fedora10/64b) kernel option. Still slow. I'm dumbfounded. Is there some problem with the 2MB L3 cache being too small for the X4 case, and causing some wild trashing of the cache that just kills performance? |
#2
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Effective speed of Phenom X3 is faster than Phenom X4 !!
I should add that X4 is 4 cores and X3 is 3 cores, in case anyone did
not realize. The big question is whether the speed gets worse because of a Phenom hardware effect, or because Firefox somehow runs WORSE with 4 cores than with one. Right now I wonder whether the latter may be the case. I recompiled Firefox 3.5.1. on the 4-core machine but that does not seem to make any difference. Firefox also uses more memory (at least temporarily) on the 4-core machine, up 2x as much easily. |
#3
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Effective speed of Phenom X3 is faster than Phenom X4 !!
reikred writes:
I recompiled Firefox 3.5.1. on the 4-core machine but that does not seem to make any difference. Firefox also uses more memory (at least temporarily) on the 4-core machine, up 2x as much easily. This all sounds very unlikely to have anything to do with the CPU... -Miles -- 「すっごい」と呟いてる。「へんてc なもんばっかり」 「そんなにへんてこ?」 「へんてこへんてこ」 そう言われると見たくなってしまう |
#4
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Effective speed of Phenom X3 is faster than Phenom X4 !!
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1 Miles Bader pravi: I recompiled Firefox 3.5.1. on the 4-core machine but that does not seem to make any difference. Firefox also uses more memory (at least temporarily) on the 4-core machine, up 2x as much easily. This all sounds very unlikely to have anything to do with the CPU... IE8 spawns additional processes, depending on the number of cores in the system (1 core = 1 process, 2 cores = 2 processes). Perhaps firefox has something similar? LP, Jure -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFKjYmWB6mNZXe93qgRAlN6AJ9n5RgnAXT8vUmjV/LaKxu5owXezQCfc4Zl GshIL8hQEiEhRDA1ODmGZPU= =WEDf -----END PGP SIGNATURE----- |
#5
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Effective speed of Phenom X3 is faster than Phenom X4 !!
I agree, it is likely not the CPU per se. More likely there is
something strange about firefox that causes it to trip up in massive fashion on 4-core cpu. The behavior is extremely reproducible. I can switch the cpu from X3 to X4 and back to X3 and then X4 again, and the slowdown is HUGE whenver I plug in the X4. |
#6
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Effective speed of Phenom X3 is faster than Phenom X4 !!
I agree, it is likely not the CPU per se. More likely there is
something strange about firefox that causes it to trip up in massive fashion on 4-core cpu. The behavior is extremely reproducible. I can switch the cpu from X3 to X4 and back to X3 and then X4 again, and the slowdown is HUGE whenver I plug in the X4. |
#7
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Effective speed of Phenom X3 is faster than Phenom X4 !!
Firefox is still single-process (but multiple threads) as of 3.5.x,
unlike Google Chrome and IE8. There is a plan to make Firefox have one process per tab or maybe window, more like Google Chrome, but it has not yet been implemented. |
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