Messages in this thread | | | Date | Wed, 25 Jun 2014 17:54:50 +0200 (CEST) | From | Jiri Kosina <> | Subject | Re: [PATCH 00/21] kGraft |
| |
On Wed, 25 Jun 2014, One Thousand Gnomes wrote:
> > this is a repost of the second round of RFC on kGraft, the linux > > kernel online patching developed at SUSE. This repost only widened the > > target audience for broader review, no code change happened. > > - wait_event_freezable(khubd_wait, > + wait_event_freezable(khubd_wait, > ({ kgr_task_safe(current); > > The changes are somewhat ugly with all the kgraft crap leaking into plces > like jbd and freezer and usb. That says to me its not well isolated and > there must be a better way of hiding that kgr stuff so we don't have to > kepe putting more code into all the kthreads, and inevitably missing them > or have people getting it wrong.
Tejun commented on this very issue during the first RFC submission a couple weeks ago. Part of his proposal was actually to take this as a good pretext to review the existing kernel threads, as the idea is that a big portion of those could easily be converted to workqueues.
It of course has its own implications, such as not being able to prioritize that easily, but there is probably a lot of low-hanging fruits where driver authors and their grandmas have been creating kthreads where workqueue would suffice.
But it's a very long term goal, and it's probably impractical to make kGraft dependent on it.
> You add instructions to various hotpaths (despite the CONFIG comment).
Kernel entry is hidden behind _TIF_WORK_SYSCALL_ENTRY and _TIF_ALLWORK_MASK, so it doesn't add any overhead if kGraft is not enabled. What other hot paths do you refer to?
> Don't get me wrong - I'd like a good working ksplice/graft !
Thanks Alan,
-- Jiri Kosina SUSE Labs
| |