Re: [RFC] [PATCH] x86: avoid per_cpu for APIC id tables

2013-07-19 Thread Ingo Molnar
* Ingo Molnar wrote: > [...] > > Also, if the goal is to pack better then we could do even better than > that: we could create a 'struct x86_apic_ids': > > struct x86_apic_ids { > u16 bios_apicid; > u16 apicid; > u32 logical_apicid; /* NOTE: does this really have to be

Re: [RFC] [PATCH] x86: avoid per_cpu for APIC id tables

2013-07-18 Thread Peter Zijlstra
On Thu, Jul 18, 2013 at 12:45:27PM +0200, Ingo Molnar wrote: > > While one could base the code (or even share) it with pipe, I'd like it > > to appear a different benchmark from the outside. Also I'm fairly sure > > they have a benchmark for this. Venki started this work, it looks like > > Andre

Re: [RFC] [PATCH] x86: avoid per_cpu for APIC id tables

2013-07-18 Thread Ingo Molnar
* Peter Zijlstra wrote: > On Thu, Jul 18, 2013 at 08:52:49AM +0200, Ingo Molnar wrote: > > > > * Andrew Hunter wrote: > > > > > Hi, I have a patch (following) that modifies handling of APIC id tables, > > > trading a small amount of space in the (NR_CPUS - nr_cpu_ids) >> 0 case > > > for > >

Re: [RFC] [PATCH] x86: avoid per_cpu for APIC id tables

2013-07-18 Thread Peter Zijlstra
On Thu, Jul 18, 2013 at 08:52:49AM +0200, Ingo Molnar wrote: > > * Andrew Hunter wrote: > > > Hi, I have a patch (following) that modifies handling of APIC id tables, > > trading a small amount of space in the (NR_CPUS - nr_cpu_ids) >> 0 case for > > faster accesses and slightly better cache lay

Re: [RFC] [PATCH] x86: avoid per_cpu for APIC id tables

2013-07-17 Thread Ingo Molnar
* Andrew Hunter wrote: > Hi, I have a patch (following) that modifies handling of APIC id tables, > trading a small amount of space in the (NR_CPUS - nr_cpu_ids) >> 0 case for > faster accesses and slightly better cache layout (as APIC ids are mostly used > cross-cpu.) I'm not an APIC expert so