On Fri, 23 Aug 2019 10:41:55 -0500, Kirk Wolf <k...@wolf-associates.com> wrote:
>I agree! > >FWIW - debugging performance of forked Unix process startup/overhead is a >mess - we had one customer who was seeing terrible performance when >fork/execing tiny little shell processes that did practically nothing. It >was only happening on one of their LPARs. The IBM Support center was >involved for a really long time, and I don't know if they ever really >figured out what was wrong. > Indeed. Ouch! But I wonder how this plays with deferred loading of program objects (I forget the proper term). Suppose a parent whose execution image is only partially loaded forks a child which accesses pages never loaded in the parent ...? So every page in the parent's execution image must be brought into storage so it can be copied to the child. >On Fri, Aug 23, 2019 at 8:24 AM Jerry Callen wrote: > >> According to the "Summary of changes for z/OS UNIX System Services >> Planning for Version 2 Release 4 (V2R4)" (see >> https://www.ibm.com/support/knowledgecenter/SSLTBW_2.4.0/com.ibm.zos.v2r4.bpxb200/bpxb2soc24.htm >> copy on write for fork() has been removed from z/OS. It will be interesting >> to benchmark the performance of fork() between 2.3 and 2.4 on a variety of >> processes. >> >> I wonder why this was done? (Hi, Peter Relson -- hint, hint...) -- gil ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
