> FWIW, I've measured the distribution of zsize (pages compressed > with frontswap) on my favorite workload (kernel "make -j2" on > mem=512M to force lots of swapping) and the mean is small, close > to 1K (PAGE_SIZE/4). I've added some sysfs shows for both > the current and cumulative distribution (0-63 bytes, 64-127 > bytes, ..., 4032-4095 bytes) for the next update. > > I tried your program on the text of Moby Dick and the mean > was still under 1500 bytes ((3*PAGE_SIZE)/8) with a good > broad distribution for zsize. Oops, on retry this morning, I am now clearly seeing the poor compression. Not sure what is different from last night, but I suspect I was "watch"ing the new sysfs output during massive swapping during the run of the test program and it wasn't updated until program completion (at which point I was no longer perusing the sysfs output). Sorry for the noise. However, now that I have a test case I am implementing another sysfs tunable to reject poorly- compressible pages that would drive the mean zsize above the tunable. Zcache will reject these pages until the mean falls below the threshold. (Setting it to PAGE_SIZE will continue current behavior, but I've set the default to (5*PAGE_SIZE)/8 for now.) Dan -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href