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Aucbvax.5624 fa.unix-wizards utzoo!decvax!ucbvax!unix-wizards Sun Dec 27 17:44:37 1981 V6 vs V7 swapping >From decvax!cwruecmp!ordy@Berkeley Sun Dec 27 17:30:57 1981 A few weeks ago I sent an item similar to this one. It apparently got lost in some mail/news/uucp problems, so here it goes again.

On vanilla V6, it is required that the text and data segments of a process come back into core (swap) physically contiguous. On vanilla V7, when both need to come back, they can come back into two disjoint pieces of memory, which should let alot more processes be core resident, and reduce core shuffling. My question of a few weeks ago asked if anybody had any comments on what effect this change made on system throughput.

Since then I have added the V7 feature to one of our V6 systems. I also had the largest piece (text or data) come in first, which the comment in the V7 code suggests should be done, but was not. The statistics I added indicate that of the complete swapins (text + data) between 1/4 and 1/3 can be fit (and on our system now are) only if broken up (I attempt to put them together if I can). Attempts to load the system and get a seat of the pants feel show that the system seems a bit more responsive.

Any comments on this area would be appreciated. We have a solid-state swapping 'disk', and are also interested in the validity of the 3 and 2 second outage/inage values.

Greg Ordy

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