Re: [PATCH 1/1] Add config option for batched hcalls
On Sat, 2010-09-25 at 22:49 -0500, Olof Johansson wrote: On Fri, Sep 24, 2010 at 04:44:15PM -0500, Will Schmidt wrote: Add a config option for the (batched) MULTITCE and BULK_REMOVE h-calls. By default, these options are on and are beneficial for performance and throughput reasons. If disabled, the code will fall back to using less optimal TCE and REMOVE hcalls. The ability to easily disable these options is useful for some of the PREEMPT_RT related investigation and work occurring on Power. Hi, I can see why it's useful to enable and disable, but these are all runtime-checked, wouldn't it be more useful to add a bootarg to handle it instead of adding some new config options that pretty much everyone will always go with the defaults on? The bits are set early, but from looking at where they're used, there doesn't seem to be any harm in disabling them later on when a bootarg is convenient to parse and deal with? It has the benefit of easier on/off testing, if that has any value for production debug down the road. Hi Olof, Thats a good idea, let me poke at this a bit more, see if I can get bootargs for this. Thanks, -Will -Olof ___ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
Re: [PATCH 1/1] Add config option for batched hcalls
On Fri, Sep 24, 2010 at 04:44:15PM -0500, Will Schmidt wrote: Add a config option for the (batched) MULTITCE and BULK_REMOVE h-calls. By default, these options are on and are beneficial for performance and throughput reasons. If disabled, the code will fall back to using less optimal TCE and REMOVE hcalls. The ability to easily disable these options is useful for some of the PREEMPT_RT related investigation and work occurring on Power. Hi, I can see why it's useful to enable and disable, but these are all runtime-checked, wouldn't it be more useful to add a bootarg to handle it instead of adding some new config options that pretty much everyone will always go with the defaults on? The bits are set early, but from looking at where they're used, there doesn't seem to be any harm in disabling them later on when a bootarg is convenient to parse and deal with? It has the benefit of easier on/off testing, if that has any value for production debug down the road. -Olof ___ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
[PATCH 1/1] Add config option for batched hcalls
Add a config option for the (batched) MULTITCE and BULK_REMOVE h-calls.
By default, these options are on and are beneficial for performance and
throughput reasons. If disabled, the code will fall back to using less
optimal TCE and REMOVE hcalls. The ability to easily disable these
options is useful for some of the PREEMPT_RT related investigation and
work occurring on Power.
Signed-off-by: Will Schmidt will_schm...@vnet.ibm.com
cc: Anton Blanchard an...@samba.org
cc: Benjamin Herrenschmidt b...@kernel.crashing.org
---
diff --git a/arch/powerpc/platforms/pseries/Kconfig
b/arch/powerpc/platforms/pseries/Kconfig
index f0e6f28..0b5e6a9 100644
--- a/arch/powerpc/platforms/pseries/Kconfig
+++ b/arch/powerpc/platforms/pseries/Kconfig
@@ -81,3 +81,23 @@ config DTL
which are accessible through a debugfs file.
Say N if you are unsure.
+
+config BULK_REMOVE
+ bool Enable BULK_REMOVE
+ depends on PPC_PSERIES
+ default y
+ help
+ Enable the BULK_REMOVE option for the hash page code.
+ This relies on a hcall-bulk firmware feature, and
+ should be enabled for performance throughput.
+
+config MULTITCE
+ bool Enable MultiTCE
+ depends on PPC_PSERIES
+ default y
+ help
+ Enable the Multi-TCE code, allowing a single hcall to
+ update multiple TCE entries at one time. This relies
+ on a hcall-multi-tce firmware feature, and should be
+ enabled for performance throughput.
+
diff --git a/arch/powerpc/platforms/pseries/firmware.c
b/arch/powerpc/platforms/pseries/firmware.c
index 0a4d8c..4327064 100644
--- a/arch/powerpc/platforms/pseries/firmware.c
+++ b/arch/powerpc/platforms/pseries/firmware.c
@@ -51,9 +51,13 @@ firmware_features_table[FIRMWARE_MAX_FEATURES] = {
{FW_FEATURE_VIO,hcall-vio},
{FW_FEATURE_RDMA, hcall-rdma},
{FW_FEATURE_LLAN, hcall-lLAN},
+#if defined(CONFIG_BULK_REMOVE)
{FW_FEATURE_BULK_REMOVE,hcall-bulk},
+#endif
{FW_FEATURE_XDABR, hcall-xdabr},
+#if defined(CONFIG_MULTITCE)
{FW_FEATURE_MULTITCE, hcall-multi-tce},
+#endif
{FW_FEATURE_SPLPAR, hcall-splpar},
};
/* Build up the firmware features bitmask using the contents of
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