Date: Sat, 17 Aug 2019 17:42:01 +0000 (UTC) From: Mateusz Guzik <mjg@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r351173 - head/sys/kern Message-ID: <201908171742.x7HHg1x5070234@repo.freebsd.org>
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Author: mjg Date: Sat Aug 17 17:42:01 2019 New Revision: 351173 URL: https://svnweb.freebsd.org/changeset/base/351173 Log: fork: stop skipping < 100 ids on wrap around Code doing this is commented with a claim that these IDs are occupied by daemons, but that's demonstrably false. To an extent the range is used by init and kernel processes (and on sufficiently big machines it indeed is fully populated). On a sample box 40-way box the highest id in the range is 63. On a different one it is 23. Just use the range. Sponsored by: The FreeBSD Foundation Modified: head/sys/kern/kern_fork.c Modified: head/sys/kern/kern_fork.c ============================================================================== --- head/sys/kern/kern_fork.c Sat Aug 17 17:22:08 2019 (r351172) +++ head/sys/kern/kern_fork.c Sat Aug 17 17:42:01 2019 (r351173) @@ -258,20 +258,13 @@ fork_findpid(int flags) } mtx_lock(&procid_lock); retry: - /* - * If the process ID prototype has wrapped around, - * restart somewhat above 0, as the low-numbered procs - * tend to include daemons that don't exit. - */ - if (trypid >= pid_max) { - trypid = trypid % pid_max; - if (trypid < 100) - trypid += 100; - } + if (trypid >= pid_max) + trypid = 2; bit_ffc_at(&proc_id_pidmap, trypid, pid_max, &result); if (result == -1) { - trypid = 100; + KASSERT(trypid != 2, ("unexpectedly ran out of IDs")); + trypid = 2; goto retry; } if (bit_test(&proc_id_grpidmap, result) ||
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