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Diffstat (limited to 'open_issues/smp.mdwn')
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1 files changed, 83 insertions, 18 deletions
diff --git a/open_issues/smp.mdwn b/open_issues/smp.mdwn index 89474d25..ce2c2ce2 100644 --- a/open_issues/smp.mdwn +++ b/open_issues/smp.mdwn @@ -12,36 +12,101 @@ License|/fdl]]."]]"""]] [[!tag open_issue_glibc open_issue_gnumach open_issue_hurd]] -See also the [[FAQ entry|faq/smp]]. +<!-- This paragraph is parapharisg the wikipedia page +https://en.wikipedia.org/wiki/Symmetric_multiprocessing#Advantages/Disadvantages +--> + +SMP stands for Symmetric multiprocessing, which is a computer that has numerous +identical processors connected to a single shared main memory. All processors +are controlled by one single operating system, and each processor can access all +devices. Operating systems with SMP can provide more performance, but it is not +trivial to do so. It is a little like having a packed board meeting. More +people in the room potentially means more can get done, but only one person can +speak at a time. Scheduling everyone to speak can be quite an involved task. + + + + NOTE: Many of the veteran Hurd developers consider this task too large for a Google summer of code project. + +<!-- +This svg is cc attribute +https://en.wikipedia.org/wiki/File:SMP_-_Symmetric_Multiprocessor_System.svg --> + +[[!img images/smp.svg size="700x"]] +<!-- most of this page is taken from https://gitlab.com/snippets/1756024#solution --> -# IRC, freenode, #hurd, 2012-09-30 +# Current Status - <braunr> i expect smp to be our next gsoc project +As of September 2024, the SMP support is implemented for i386 with +working internet, because it boots with only one cpu in the default +processor set. The slave processors are temporarily disabled until +they can be safely used per task. We are unable to turn on the full +set at boot time due to race bugs. Debian Hurd provides SMP enabled +GNU Mach kernels. +# How to test the current SMP support -## IRC, freenode, #hurd, 2013-01-02 +The easiest way to test the SMP support, is via the [[qemu +guide|https://www.gnu.org/software/hurd/hurd/running/qemu.html]]. +Once you have the Hurd running you can build an SMP enabled GNU Mach. - <braunr> i'd like to mentor someone for adding smp to gnumach + $ git clone git://git.savannah.gnu.org/hurd/gnumach.git + $ cd gnumach + $ autoreconf -i + $ mkdir build + $ cd build + $ ../configure --enable-ncpus=4 --enable-kdb + $ make gnumach.gz + $ su + # mv /boot/gnumach-1.8-486.gz /boot/gnumach-1.8-486.gz.bak + # cp gnumach.gz /boot/gnumach-1.8-486.gz +You may optionally update `/boot/grub/grub.cfg` change `hd0` to `wd0` +and add `console=com0` -## IRC, freenode, #hurd, 2013-03-14 + /boot/gnumach-1.8-486.gz root=part:2:device:wd0 console=com0 - <braunr> but i'm afraid we'll have to fight obscur smp-safety issues - <braunr> for one, drivers are much probably not smp safe and would require - a big kernel lock - <braunr> userspace (such as signal delivery in libc) might be affected too - <braunr> smp isn't that easy +update `/etc/fstab` and update `wd0` instead of `hd0`. + /dev/wd0s2 / ext2 defaults 0 1 + /dev/wd0s1 none swap sw 0 0 -## Richard, 2013-03-20 +You can shutdown via `/sbin/poweroff`. -This task actually looks too big for a GSoC project. +start qemu with `-smp 4` and add `-nographic` if you want to use `com0`. + $ qemu-system-i386 -M q35,accel=kvm -smp 4 -m 2G -net \ + user,hostfwd=tcp::2223-:22 -net nic -hda debian-hurd-VERSION.img \ + -nographic -## IRC, freenode, #hurd, 2013-09-30 +To test smp: + + $ sudo /path/to/smp /bin/bash + $ stress -c 7 + +smp.c source can be found +[[here|https://lists.gnu.org/archive/html/bug-hurd/2024-02/msg00088.html]]. + +## References +- [Comments about the project bug-hurd +maillist](https://lists.gnu.org/archive/html/bug-hurd/2018-08/msg00048.html) +- [Initial thread in bug-hurd +maillist](https://lists.gnu.org/archive/html/bug-hurd/2018-06/msg00048.html) +- [SMP in GNU/Hurd FAQ](https://www.gnu.org/software/hurd/faq/smp.html) +- [GNU Mach git repository](https://git.savannah.gnu.org/cgit/hurd/gnumach.git) +- [GNU Mach reference manual](https://www.gnu.org/software/hurd/gnumach-doc/) +- [**MultiProcessor Specification**](https://pdos.csail.mit.edu/6.828/2011/readings/ia32/MPspec.pdf) +- [**ACPI Specification**](http://www.uefi.org/sites/default/files/resources/ACPI%206_2_A_Sept29.pdf) +- [Mach boot trace](https://www.gnu.org/software/hurd/microkernel/mach/gnumach/boot_trace.html) +- [SPL man page](https://man.openbsd.org/spl) +- [Book: The Mach System](http://codex.cs.yale.edu/avi/os-book/OS9/appendices-dir/b.pdf) +- [Book: Mach3 Mysteries](http://www.nv50.0fees.net/Doc/Mach3Mysteries.pdf) +- [X15 operating system](https://www.sceen.net/x15) +- [Symmetric Multiprocessing - OSDev Wiki](https://wiki.osdev.org/Symmetric_Multiprocessing) +- [**Intel® 64 and IA-32 Architectures Software Developer’s Manuals**](https://software.intel.com/sites/default/files/managed/39/c5/325462-sdm-vol-1-2abcd-3abcd.pdf) +- [**Intel Developer Guide, Volume 3: System Programming Guide**](https://software.intel.com/sites/default/files/managed/a4/60/325384-sdm-vol-3abcd.pdf) + + +See also the [[FAQ entry|faq/smp]]. - <braunr> also, while the problem with hurd is about I/O, it's actually a - lot more about caching, and even with more data cached in, the true - problem is contention, in which case having several processors would - actually slow things down even more |