Change Details

case 1: % make buildworld -j 300 While above using swap space and have sufficient space to take one off, % swapoff <swap-device> case 2: % mount -t tmpfs tmpfs /mnt/tmp % dd if=/dev/zero of=/mnt/tmp/bigfile bs=1M count=10000 While above using swap space and have sufficient space to take one off, % swapoff <swap-device>

case 1: % make buildworld -j 300 While above using swap space and have sufficient space to take one off, % swapoff <swap-device> case 2: % mount -t tmpfs tmpfs /mnt/tmp % dd if=/dev/zero of=/mnt/tmp/bigfile bs=1M count=10000 While above using swap space and have sufficient space to take one off, % swapoff <swap-device> Performance Measurement: Objective: Find how much "swapoff" became faster at best case. Setting: FreeBSD 12.0-STABLE on VMWare with 2GB of memory and 2GB swap space on SSD. Commands: % mount -t tmpfs tmpfs /mnt/tmp % dd if=/dev/zero of=/mnt/tmp/1GB bs=1M count=1024 % dd if=/dev/zero of=/mnt/tmp/out bs=1M count=1900 % rm /mnt/tmp/out % time swapff /dev/ada0s1b Details: 1. Create "1GB" file and swap it out with "out". 2. Delete "out" file so that "swapoff" will swap back in "1GB" file. 3. Measure time and compare. Result: Wall clock time speed up was about 7 times faster. Patched version also had about 18 times lesser page-in operations while each one took about 18 pages compare to 1 page at a time without the patch. ==> old.txt <== unpatched# sysctl -a | grep v_swap | grep in vm.stats.vm.vm_swappgsin: 1 vm.stats.vm.vm_swapin: 1 unpatched# time swapoff /dev/ada0s1b 0.000u 11.351s 0:47.50 23.8% 20+357k 0+0io 0pf+0w unpatched# sysctl -a | grep v_swap | grep in vm.stats.vm.vm_swappgsin: 263858 vm.stats.vm.vm_swapin: 263858 ==> new.txt <== patched# sysctl -a | grep v_swap | grep in vm.stats.vm.vm_swappgsin: 1 vm.stats.vm.vm_swapin: 1 patched# time swapoff /dev/ada0s1b 0.000u 0.765s 0:07.93 9.5% 15+272k 4+0io 2pf+0w patched# sysctl -a | grep v_swap | grep in vm.stats.vm.vm_swappgsin: 266696 vm.stats.vm.vm_swapin: 14596

case 1: % make buildworld -j 300 While above using swap space and have sufficient space to take one off, % swapoff <swap-device> case 2: % mount -t tmpfs tmpfs /mnt/tmp % dd if=/dev/zero of=/mnt/tmp/bigfile bs=1M count=10000 While above using swap space and have sufficient space to take one off, % swapoff <swap-device> Performance Measurement: Objective: Find how much "swapoff" became faster at best case. Setting: FreeBSD 12.0-STABLE on VMWare with 2GB of memory and 2GB swap space on SSD. Commands: % mount -t tmpfs tmpfs /mnt/tmp % dd if=/dev/zero of=/mnt/tmp/1GB bs=1M count=1024 % dd if=/dev/zero of=/mnt/tmp/out bs=1M count=1900 % rm /mnt/tmp/out % time swapff /dev/ada0s1b Details: 1. Create "1GB" file and swap it out with "out". 2. Delete "out" file so that "swapoff" will swap back in "1GB" file. 3. Measure time and compare. Result: Wall clock time speed up was about 7 times faster. Patched version also had about 18 times lesser page-in operations while each one took about 18 pages compare to 1 page at a time without the patch. ==> old.txt <== unpatched# sysctl -a | grep v_swap | grep in vm.stats.vm.vm_swappgsin: 1 vm.stats.vm.vm_swapin: 1 unpatched# time swapoff /dev/ada0s1b 0.000u 11.351s 0:47.50 23.8% 20+357k 0+0io 0pf+0w unpatched# sysctl -a | grep v_swap | grep in vm.stats.vm.vm_swappgsin: 263858 vm.stats.vm.vm_swapin: 263858 ==> new.txt <== patched# sysctl -a | grep v_swap | grep in vm.stats.vm.vm_swappgsin: 1 vm.stats.vm.vm_swapin: 1 patched# time swapoff /dev/ada0s1b 0.000u 0.765s 0:07.93 9.5% 15+272k 4+0io 2pf+0w patched# sysctl -a | grep v_swap | grep in vm.stats.vm.vm_swappgsin: 266696 vm.stats.vm.vm_swapin: 14596