On 13/11/17 11:06, Quan Xu wrote: > From: Quan Xu <quan....@gmail.com> > > So far, pv_idle_ops.poll is the only ops for pv_idle. .poll is called > in idle path which will poll for a while before we enter the real idle > state. > > In virtualization, idle path includes several heavy operations > includes timer access(LAPIC timer or TSC deadline timer) which will > hurt performance especially for latency intensive workload like message > passing task. The cost is mainly from the vmexit which is a hardware > context switch between virtual machine and hypervisor. Our solution is > to poll for a while and do not enter real idle path if we can get the > schedule event during polling. > > Poll may cause the CPU waste so we adopt a smart polling mechanism to > reduce the useless poll. > > Signed-off-by: Yang Zhang <yang.zhang...@gmail.com> > Signed-off-by: Quan Xu <quan....@gmail.com> > Cc: Juergen Gross <jgr...@suse.com> > Cc: Alok Kataria <akata...@vmware.com> > Cc: Rusty Russell <ru...@rustcorp.com.au> > Cc: Thomas Gleixner <t...@linutronix.de> > Cc: Ingo Molnar <mi...@redhat.com> > Cc: "H. Peter Anvin" <h...@zytor.com> > Cc: x...@kernel.org > Cc: virtualizat...@lists.linux-foundation.org > Cc: linux-ker...@vger.kernel.org > Cc: xen-de...@lists.xenproject.org
Hmm, is the idle entry path really so critical to performance that a new pvops function is necessary? Wouldn't a function pointer, maybe guarded by a static key, be enough? A further advantage would be that this would work on other architectures, too. Juergen _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org https://lists.xen.org/xen-devel
