Messages in this thread | | | Date | Sat, 04 Jan 2003 23:31:11 -0500 | From | Jason Papadopoulos <> | Subject | [PATCH] rewritten page coloring for 2.4.20 kernel |
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Hello. After a year in stasis, I've completely rebuilt my kernel patch that implements page coloring. Improvements include:
- Page coloring is now hardwired into the kernel. The hash queues now use bootmem, and page coloring is always on. The patch still creates /proc/page_color for statistics, but that will go away in time.
- Automatic detection of external cache size on many architectures. I have no idea if any of this code works, since I don't have any of the target machines. The preferred way to initialize the coloring is by passing "page_color=<external cache size in kB>" as a boot argument.
- NUMA-safe, discontig-safe
Right now the actual page coloring algorithm is the same as in previous patches, and performs the same. In the next few weeks I'll be trying new ideas that will hopefully reduce fragmentation and increase performance. This is an early attempt to get some feedback on mistakes I may have made.
lmbench shows no real gains or losses compared to an unpatched kernel; some of the page fault and protection fault times are slightly slower, but it's close to the rounding error over five lmbench runs.
Here are all the performance results I have for the patch:
1. Compile of 2.4.20 kernel with gcc 3.1.1 on 466MHz DS10 Alphaserver with 2MB cache: repeatable 1% speedup (573 sec vs. 579 sec)
2. 1000x1000 matrix multiply: 10% speedup on Athlon II with 512kB cache (Dieter Nützel)
3. Without page coloring, the alpha gets 80% of max theoretical bandwidth for working sets at most 1/8 the size of its L2 cache. For larger working sets than that the achieved bandwidth is only 30%-50% of max. With page coloring, the 80% figure applies to the entire L2 cache.
4. FFTW (alpha): 30% speedup for 64k-point FFTs, 20% speedup for 1M-point FFTs
Patch is available at
www.boo.net/~jasonp/page_color-2.4.20-20030104.patch
Thanks in advance for any feedback. jasonp - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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