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e515352f84
This is an evolution of a Perl script that I originally wrote for this bug: https://bugzilla.redhat.com/show_bug.cgi?id=1478201
95 lines
2.5 KiB
Perl
Executable File
95 lines
2.5 KiB
Perl
Executable File
#!/usr/bin/perl -w
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# libguestfs
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# Copyright (C) 2018 Red Hat Inc.
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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# From painful experience we know that changes to the kernel can
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# suddenly change the maximum number of disks we can add to the
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# appliance. This script uses a simple binary search to find the
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# current maximum.
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#
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# To test different kernels you may want to do:
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# rm -rf /var/tmp/.guestfs-*
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# export SUPERMIN_KERNEL=/boot/vmlinuz-...
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# export SUPERMIN_MODULES=/lib/modules/...
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# ./max-disks.pl
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#
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# See also:
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# https://bugzilla.redhat.com/show_bug.cgi?id=1478201#c4
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use strict;
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use Sys::Guestfs;
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$| = 1;
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my $low = 1;
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my $high = 2048; # Will never test higher than this.
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my $mid = 1024;
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# Get the kernel under test.
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my $g = Sys::Guestfs->new ();
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$g->launch ();
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my %kernel = $g->utsname;
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$g->close ();
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sub test_mid
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{
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my ($ret, %k);
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eval {
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my $g = Sys::Guestfs->new ();
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for (my $i = 0; $i < $mid; ++$i) {
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$g->add_drive_scratch (1024*1024);
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}
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$g->launch ();
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%k = $g->utsname;
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$g->shutdown ();
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};
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if ($@) {
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printf ("%d => bad\n", $mid);
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$ret = 0;
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}
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else {
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printf ("%d => good\n", $mid);
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$ret = 1;
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}
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die "kernel version changed during test!\n"
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if exists $k{uts_release} && $k{uts_release} ne $kernel{uts_release};
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return $ret;
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}
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for (;;) {
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if (test_mid ()) {
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# good, so try higher
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$low = $mid;
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}
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else {
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# bad, so try lower
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$high = $mid;
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}
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$mid = int (($high+$low) / 2);
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if ($mid == $high || $mid == $low) {
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printf("kernel: %s %s (%s)\n",
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$kernel{uts_sysname}, $kernel{uts_release},
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$kernel{uts_machine});
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# +1 because of the appliance disk.
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printf ("max disks = %d\n", $mid+1);
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exit 0;
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}
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}
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