On 08/07/2012 03:23 PM, Seth Jennings wrote: > On 07/27/2012 01:18 PM, Seth Jennings wrote: >> Some benchmarking numbers demonstrating the I/O saving that can be had >> with zcache: >> >> https://lkml.org/lkml/2012/3/22/383 > > There was concern that kernel changes external to zcache since v3.3 may > have mitigated the benefit of zcache. So I re-ran my kernel building > benchmark and confirmed that zcache is still providing I/O and runtime > savings. There was a request made to test with even greater memory pressure to demonstrate that, at some unknown point, zcache doesn't have real problems. So I continued out to 32 threads: N=4..20 is the same data as before except for the pswpin values. I found a mistake in the way I computed pswpin that changed those values slightly. However, this didn't change the overall trend. I also inverted the %change fields since it is a percent change vs the normal case. I/O (in pages) normal zcache change N pswpin pswpout majflt I/O sum pswpin pswpout majflt I/O sum %I/O 4 0 2 2116 2118 0 0 2125 2125 0% 8 0 575 2244 2819 0 4 2219 2223 -21% 12 1979 4038 3226 9243 1269 2519 3871 7659 -17% 16 21568 47278 9426 78272 7770 15598 9372 32740 -58% 20 50307 127797 15039 193143 20224 40634 17975 78833 -59% 24 186278 364809 45052 596139 47406 90489 30877 168772 -72% 28 274734 777815 53112 1105661 134981 307346 63480 505807 -54% 32 988530 2002087 168662 3159279 324801 723385 140288 1188474 -62% Runtime (in seconds) N normal zcache %change 4 126 127 1% 8 124 124 0% 12 131 133 2% 16 189 156 -17% 20 261 235 -10% 24 513 288 -44% 28 556 434 -22% 32 1463 745 -49% %CPU utilization (out of 400% on 4 cpus) N normal zcache %change 4 254 253 0% 8 261 263 1% 12 250 248 -1% 16 173 211 22% 20 124 140 13% 24 64 114 78% 28 59 76 29% 32 23 45 96% The ~60% I/O savings holds even out to 32 threads, at which point the non-zcache case has 12GB of I/O and is taking 12x longer to complete. Additionally, the runtime savings increases significantly beyond 20 threads, even though the absolute runtime is suboptimal due to the extreme memory pressure. Seth -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>