Date: Sat, 07 Oct 2023 00:02:42 +0000 From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 274316] excessive memory consumed by static_single_cpu_mask Message-ID: <bug-274316-227-ba5DjCFwhv@https.bugs.freebsd.org/bugzilla/> In-Reply-To: <bug-274316-227@https.bugs.freebsd.org/bugzilla/> References: <bug-274316-227@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D274316 --- Comment #2 from Ed Maste <emaste@freebsd.org> --- We can switch to run-time sizing for these, but there's a very interesting observation used by Linux that we can adopt, to significantly reduce the me= mory used. We have (currently) MAXCPU count of cpuset_ts, each with one CPU set. Note = that all but one of the longs making up each cpuset_t is zero. If n=3D__bitset_words(MAXCPU) then cpuset_t is an array of long __bits[n]. = If we have (n-1) long zeros, 0x1, (n-1) long zeros, 0x2, (n-1) long zeros, and so= on, with an appropriate offset we can use that same 0x1 for: 0000000000000000 0000000000000000 ... 0000000000000000 0000000000000001 0000000000000000 0000000000000000 ... 0000000000000001 0000000000000000 ... 0000000000000000 0000000000000001 ... 0000000000000000 0000000000000000 0000000000000001 0000000000000000 ... 0000000000000000 0000000000000000 and so on for 0x2, etc. --=20 You are receiving this mail because: You are the assignee for the bug.=
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