Messages in this thread | | | Subject | Re: [PATCH/RFT 5/5] CLOCK-Pro page replacement | From | Song Jiang <> | Date | Thu, 11 Aug 2005 16:08:15 -0600 |
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My current test focuses on the looping case, where I repeatedly scan a file whose size is larger than the memory size but less than two times of memory sizes. My initial results are as follows:
My machine has 2GB memory. The size of the file to be scanned is 2.5GB. I looped for 4 time. The times and associated disk bandwidths for each loop are below:
loop 0 time = 34.229424s bandwith = 76.58MB loop 1 time = 37.574041s bandwith = 69.76MB loop 2 time = 38.181791s bandwith = 68.65MB loop 3 time = 38.141794s bandwith = 68.72MB
This shows that the current patches cannot do a better job than the original kernel, which notoriously underperforms for the case -- no matter how many times the file is accessed, no hits at all. Meanwhile, Clock-Pro is supposed to do a better job, because part of the file can be protected in the active list and get a decent number of hits.
Here is from /proc/meminfo:
Active: 11356 kB Inactive: 1994400 kB
So no file pages are promoted into the active list, just as in the original kernel.
Here is from /proc/refaults:
Refault distance Hits 0 - 32768 192 32768 - 65536 269 65536 - 98304 447 98304 - 131072 603 131072 - 163840 1087 163840 - 196608 909 196608 - 229376 558 229376 - 262144 404 262144 - 294912 287 294912 - 327680 191 327680 - 360448 79 360448 - 393216 68 393216 - 425984 41 425984 - 458752 45 458752 - 491520 31 New/Beyond 491520 2443
In the statistic, we do see many hits at the distance of around 150,000 pages. If we consider the inactive list size (1.9GB), this position corresponds to the file size. However, if everything happens as expected, all the hits should happen at the distance. Unfortunately, there are also many hits listed as New/Beyond. Because "Beyond"s should not be there, are they all "New"s? Futhermore, I didn't see where the refault_histogram statistics get reset, though they almost stop increasing after the first run. Can you show me that?
Song Jiang at LANL
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