Re: [PATCH 2/3] arm/arm64: speed up spinlocks and atomic ops

2015-06-29 Thread Christoffer Dall
On Mon, Jun 29, 2015 at 12:44:27PM +0200, Andrew Jones wrote: > On Mon, Jun 29, 2015 at 12:28:32PM +0200, Christoffer Dall wrote: > > On Thu, Jun 25, 2015 at 06:12:18PM +0200, Andrew Jones wrote: > > > spinlock torture tests made it clear that checking mmu_enabled() > > > every time we call spin_lo

Re: [PATCH 2/3] arm/arm64: speed up spinlocks and atomic ops

2015-06-29 Thread Andrew Jones
On Mon, Jun 29, 2015 at 12:28:32PM +0200, Christoffer Dall wrote: > On Thu, Jun 25, 2015 at 06:12:18PM +0200, Andrew Jones wrote: > > spinlock torture tests made it clear that checking mmu_enabled() > > every time we call spin_lock is a bad idea. > > why a bad idea? Does it break, is it slow? Ju

Re: [PATCH 2/3] arm/arm64: speed up spinlocks and atomic ops

2015-06-29 Thread Christoffer Dall
On Thu, Jun 25, 2015 at 06:12:18PM +0200, Andrew Jones wrote: > spinlock torture tests made it clear that checking mmu_enabled() > every time we call spin_lock is a bad idea. why a bad idea? Does it break, is it slow? > As most tests will > want the MMU enabled the entire time, then just hard co

Re: [PATCH 2/3] arm/arm64: speed up spinlocks and atomic ops

2015-06-25 Thread Andrew Jones
On Thu, Jun 25, 2015 at 06:23:48PM +0200, Paolo Bonzini wrote: > > > On 25/06/2015 18:12, Andrew Jones wrote: > > spinlock torture tests made it clear that checking mmu_enabled() > > every time we call spin_lock is a bad idea. As most tests will > > want the MMU enabled the entire time, then just

Re: [PATCH 2/3] arm/arm64: speed up spinlocks and atomic ops

2015-06-25 Thread Paolo Bonzini
On 25/06/2015 18:12, Andrew Jones wrote: > spinlock torture tests made it clear that checking mmu_enabled() > every time we call spin_lock is a bad idea. As most tests will > want the MMU enabled the entire time, then just hard code > mmu_enabled() to true. Tests that want to play with the MMU ca

[PATCH 2/3] arm/arm64: speed up spinlocks and atomic ops

2015-06-25 Thread Andrew Jones
spinlock torture tests made it clear that checking mmu_enabled() every time we call spin_lock is a bad idea. As most tests will want the MMU enabled the entire time, then just hard code mmu_enabled() to true. Tests that want to play with the MMU can be compiled with CONFIG_MAY_DISABLE_MMU to get th