Messages in this thread | | | Date | Mon, 07 Feb 2011 16:58:16 +0100 | From | Jan Kiszka <> | Subject | Re: [PATCH] KVM: x86: Convert tsc_write_lock to raw_spinlock |
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On 2011-02-07 16:52, Avi Kivity wrote: > On 02/07/2011 05:38 PM, Jan Kiszka wrote: >>> >>> I don't know as it is allowed to sleep, it doesn't call any sleeping >>> functions to my knowledge. What worries me in the RT case is that the >>> spinlock acquired for hardware_enable might be preempted and run on >>> another CPU, which obviously isn't what you want. >> >> I see now, there are calls to raw_smp_processor_id. >> >> I think it's best to make this a raw lock. At this chance, some >> read-only users of vm_list should be rcu'ified. Will have a look. > > vm_list is rarely used, for either read or write. I don't see the need > to rcu it.
Avoid that code under this lock expands the preempt-disabled period, specifically under -rt, and specifically as the number of objects over which we loop is user-defined.
Jan
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