From: Michael Neuling <mikey@neuling•org>
To: Haren Myneni <haren@linux•vnet.ibm.com>
Cc: anton@au1•ibm.com, paulus@samba•org, linuxppc-dev@lists•ozlabs.org
Subject: Re: [PATCH 0/6] powerpc: SMT priority (PPR) save and restore
Date: Thu, 01 Nov 2012 11:44:49 +1100 [thread overview]
Message-ID: <25370.1351730689@neuling.org> (raw)
In-Reply-To: <1351666171.32304.10.camel@hbabu-laptop>
Haren Myneni <haren@linux•vnet.ibm.com> wrote:
> [PATCH 0/6] powerpc: SMT priority (PPR) save and restore
>
> On P7 systems, users can define SMT priority levels 2,3 and 4 for
> processes so that some can run higher priority than the other ones.
> In the current kernel, the default priority is set to 4 which prohibits
> processes for using higher priority. Also the kernel boosts the priority to
> 4 during exceptions without saving the user defined priorities when
> the task enters the kernel. So we will be loosing the process PPR value
> and can not be restored it back when the task exits the kernel.
>
> This patchset implements saving and restore the user defined PPR value
> for all tasks.
>
> With null_syscall testcase (http://ozlabs.org/~anton/junkcode/null_syscall.c),
> this feature takes around extra 10 CPU cycles on average for 25 samples.
Haren,
This version doesn't do PPR save/restore over syscall, so is this above
statement still true? null_syscall shouldn't be effected at all, right?
Mikey
>
> Haren Myneni (6):
> powerpc: Move branch instruction from ACCOUNT_CPU_USER_ENTRY to caller
> powerpc: Define CPU_FTR_HAS_PPR
> powerpc: Increase exceptions arrays in paca struct to save PPR
> powerpc: Define ppr in thread_struct
> powerpc: Macros for saving/restore PPR
> powerpc: Implement PPR save/restore
>
> arch/powerpc/include/asm/cputable.h | 6 ++-
> arch/powerpc/include/asm/exception-64s.h | 45 ++++++++++++++++++++++++++----
> arch/powerpc/include/asm/paca.h | 6 ++--
> arch/powerpc/include/asm/ppc_asm.h | 27 ++++++++++++++++-
> arch/powerpc/include/asm/processor.h | 6 ++++
> arch/powerpc/include/asm/reg.h | 1 +
> arch/powerpc/kernel/asm-offsets.c | 1 +
> arch/powerpc/kernel/entry_64.S | 6 +++-
> arch/powerpc/kernel/exceptions-64e.S | 3 +-
> arch/powerpc/kernel/exceptions-64s.S | 15 +++++----
> arch/powerpc/kernel/process.c | 2 +
> 11 files changed, 96 insertions(+), 22 deletions(-)
>
>
>
next prev parent reply other threads:[~2012-11-01 0:44 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-31 6:49 [PATCH 0/6] powerpc: SMT priority (PPR) save and restore Haren Myneni
2012-11-01 0:44 ` Michael Neuling [this message]
2012-11-02 1:20 ` Haren Myneni
-- strict thread matches above, loose matches on Subject: below --
2012-12-07 7:44 Haren Myneni
2012-09-09 11:32 Haren Myneni
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