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Diffstat (limited to 'faq')
| -rw-r--r-- | faq/smp.mdwn | 31 |
1 files changed, 22 insertions, 9 deletions
diff --git a/faq/smp.mdwn b/faq/smp.mdwn index c0133b80..ee0bf53f 100644 --- a/faq/smp.mdwn +++ b/faq/smp.mdwn @@ -13,21 +13,34 @@ License|/fdl]]."]]"""]] [[!meta title="Does GNU/Hurd support SMP/Multicore?"]] -The Hurd servers themselves are multithreaded, so they should be able to take benefit of the parallelism brought by SMP/Multicore boxes. This has however never been tested yet because of the following. +The Hurd servers themselves are multithreaded, so they should be able to +benefit of the parallelism brought by SMP/Multicore boxes. +This needs testing as SMP support has recently been added to Mach. [[microkernel/Mach]] used to be running on SMP boxes like the [[!wikipedia Intel_iPSC/860]], so principally has the required infrastructure. It has -however not yet been enhanced to support nowadays' SMP standards like ACPI, -etc. Also, [[GNU Mach|microkernel/mach/gnumach]]'s Linux device driver glue -code likely isn't SMP-safe. As this glue code layer is not used in the -[[microkernel/mach/gnumach/ports/Xen]] port of GNU Mach, the plan is to try it -in this enviroment first. +recently been enhanced to support nowadays' SMP standards like ACPI. -[[!tag open_issue_gnumach open_issue_xen]] +However, [[GNU Mach|microkernel/mach/gnumach]]'s Linux device driver glue +code isn't SMP-safe so build with --disable-linux-groups to test SMP and use +rumpdisk to provide disk access. -That is why for now GNU/Hurd will only use one logical processor (i.e. one core or one thread, depending on the socket type). +To build an SMP supported gnumach with kdb: +../configure --enable-ncpus=8 --enable-kdb --enable-apic --disable-linux-groups -Once this issue is solved, there are follow-up issues about +This will by default allow you to boot with one core isolated to the default +processor set, and all the other detected cpus will be in the slave processor set. +The slave processors need to be enabled per-task using RPCs to manipulate processor sets. + +See https://lists.gnu.org/archive/html/bug-hurd/2024-02/msg00088.html for a test program +that can enable a task to use the slave processors by calling ./smp /bin/bash for example. + +Unfortunately, there are race conditions causing hangs or crashes in Mach when attempting +to boot a full SMP system, (if you revert the slave processor pinning commit). +This is what needs to be debugged one-by-one by running each translator using ./smp until +we can squash these race condition bugs. + +There are follow-up issues about [[open_issues/multiprocessing]] and [[open_issues/multithreading]]. [[Project idea|open_issues/smp]]. |