The following is from a presentation made on 86.10.07 at the SEAS meeting on Jersey. List of SEAS meetings: http://www.daube.ch/share/seas01.html#places
It describes a series of test on production VM/370 release 6 system comparing PAM/CDF, PAM/EDF, and 4k/EDF. Lots of past PAM references http://www.garlic.com/~lynn/subtopic.html#pam Comparison of PAM, CDF and EDF pam/cdf pam/edf 4k/edf runl 2.89/39l0/33. 3.28/4103/4l. 3 72/1978/95. run2 2.90/3768/49. 3.32/4ll5/54. 3.65/1965/79. run3 3.01/3749/47. 3.35/4l23/8l. 3.66/1932/77. runq 2.94/4033/34. 3.46/3975/46. 3.66/1920/63. run5 3.0l/3472/36. 3.62/3884/68. 3.75/1948/85. run6 3.08/3776/70. 3.46/3784/60. 3.79/1986/84. run7 3.l3/3740/57. 3.37/3979/46. 3.75/1977/84 run8 2.99/3868/87. 3.4l/3836/52.. 3.77/1958/88. system CPU I/O elapsed avg. avg. avg. 4k/EDF 3.72 1958 81. PAM/EDF 3.4l 3836 56. PAM/CDF 3.02 3790 52. min, min. min 4k/EDF 3.66 1920 63. PAM/EDF 3.28 3784 41. PAM/CDF 2.89 3472 33. 4k/EDF is the EDF CMS filesystem introduced in VM/370 release 6 used with 4k block option. PAM/CDF is the original CMS filesystem modified to use 4K records rather than 800 and page-map interface. PAM/EDF is the EDF CMS filesystem modified to use the page-map interface. CPU is total (combination of virtual and supervisor). The test was run on standard production system with other activity. A run consisted of doing the same exact operations involving pam/cdf filesystem, then pam/edf filesystem, then 4k/edf filesystem. This was repeated eight times and the avg. values and the minimum values used. There is not a direct comparison between 4k/edf i/o and pam i/o. For 4k/edf, I/O is reported as the number of virtual i/o operations (independent of number of records transferred). There is slight variability in 4k/edf i/o based on state of the filesystem and the number of contiguous records that might be involved for operation. For pam i/o, reported is the number of 4k page transfers (which might also include other paging operations for the virtual machine during the period and doesn't directly indicate the number of physical i/o operations). Both PAM test performed better than 4k/edf because of 1) reduced CP overhead for supporting the operation, 2) better CP logic for chaining multiple 4k transfers in single I/O, The minimum values are going to be closest to base operation excluding interferance from other workload on the system. pam/cdf is nearly twice as fast and approx. 1/4 less cpu for the workload compared to the same workload running on 4k/edf filesystem. When the science center http://www.garlic.com/~lynn/subtopic.html#545tech eventually replaced its 360/67 with 370/155, there was a port of a lot of local modifications from cp67 to vm370. another page from the same SEAS presentation Release 2.15 CSC/VM * Relocatable (floating) Shared Segments * Paging Access Method (PAM) * CP/67 Feedback controls * CP/67 Working Set controls * CP/67 GLobal LRU Page Replacement * CP/67 Fastpath * Restructured Page Supervisor * Page and Swaptable Migration * Q3 * Scheduling based on resource objectives * Resource objectives either fixed or fairshare note that much of this, I subsequently released in the resource manager ... blue letter reference in recent posting http://www.garlic.com/~lynn/2006.html#19 DCSS as SWAP disk for z/Linux a small subset of the cms & cp relocatable (floating) shared segments http://www.garlic.com/~lynn/subtopic.html#adcon (w/o paged-map support) had been released as DCSS (prior to the resource manager release). a couple other posts in this thread: http://www.garlic.com/~lynn/2006.html#17 {SPAM?} DCSS as SWAP disk for z/Linux http://www.garlic.com/~lynn/2006.html#18 DCSS as SWAP disk for z/Linux -- Anne & Lynn Wheeler | http://www.garlic.com/~lynn/
