Patchwork [1/1,v2] Add kernel parameter to disable batched hcalls

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Submitter Will Schmidt
Date Sept. 28, 2010, 5:02 p.m.
Message ID <1285693371.2843.43.camel@lexx>
Download mbox | patch
Permalink /patch/66003/
State Changes Requested
Headers show

Comments

Will Schmidt - Sept. 28, 2010, 5:02 p.m.
This introduces a pair of kernel parameters that can be used to disable
the MULTITCE and BULK_REMOVE h-calls. 

By default, those hcalls are enabled, active, and good for throughput
and performance.  The ability to disable them will be useful for some of
the PREEMPT_RT related investigation and work occurring on Power.


Signed-off-by: Will Schmidt <will_schmidt@vnet.ibm.com>
cc: Olof Johansson <olof@lixom.net>
cc: Anton Blanchard <anton@samba.org>
cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>

---

v2 - Per feedback from Olof, the code is reworked to utilize kernel
parameter runtime checks, rather than CONFIG options.
   - Added relevant change to kernel-parameters.txt
Olof Johansson - Sept. 28, 2010, 5:52 p.m.
Nice. I've got minor nits below, and you might also want to run the patch
through checkpatch and fix up some of the whitespace warnings.


-Olof

On Tue, Sep 28, 2010 at 12:02:51PM -0500, Will Schmidt wrote:
> 
> This introduces a pair of kernel parameters that can be used to disable
> the MULTITCE and BULK_REMOVE h-calls. 
> 
> By default, those hcalls are enabled, active, and good for throughput
> and performance.  The ability to disable them will be useful for some of
> the PREEMPT_RT related investigation and work occurring on Power.
> 
> 
> Signed-off-by: Will Schmidt <will_schmidt@vnet.ibm.com>
> cc: Olof Johansson <olof@lixom.net>
> cc: Anton Blanchard <anton@samba.org>
> cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> 
> ---
> 
> v2 - Per feedback from Olof, the code is reworked to utilize kernel
> parameter runtime checks, rather than CONFIG options.
>    - Added relevant change to kernel-parameters.txt
> 
> 
> 
> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
> index e2c7487..5c40801 100644
> --- a/Documentation/kernel-parameters.txt
> +++ b/Documentation/kernel-parameters.txt
> @@ -426,6 +426,10 @@ and is between 256 and 4096 characters. It is defined in the file
>  	bttv.pll=	See Documentation/video4linux/bttv/Insmod-options
>  	bttv.tuner=	and Documentation/video4linux/bttv/CARDLIST
>  
> +	bulk_remove=off	[PPC]  This parameter disables the use of the pSeries
> +			firmware feature for flushing multiple hpte entries
> +			at a time.
> +
>  	BusLogic=	[HW,SCSI]
>  			See drivers/scsi/BusLogic.c, comment before function
>  			BusLogic_ParseDriverOptions().
> @@ -1499,6 +1503,10 @@ and is between 256 and 4096 characters. It is defined in the file
>  	mtdparts=	[MTD]
>  			See drivers/mtd/cmdlinepart.c.
>  
> +	multitce=off	[PPC]  This parameter disables the use of the pSeries
> +			firmware feature for updating multiple TCE entries
> +			at a time.
> +
>  	onenand.bdry=	[HW,MTD] Flex-OneNAND Boundary Configuration
>  
>  			Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
> diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
> index 902987d..e174a2f 100644
> --- a/arch/powerpc/platforms/pseries/iommu.c
> +++ b/arch/powerpc/platforms/pseries/iommu.c
> @@ -625,3 +625,19 @@ void iommu_init_early_pSeries(void)
>  	set_pci_dma_ops(&dma_iommu_ops);
>  }
>  
> +static int __init disable_multitce(char *str)
> +{
> +	if (strcmp(str,"off")==0) {
> +		if (firmware_has_feature(FW_FEATURE_LPAR)) {
> +			if (firmware_has_feature(FW_FEATURE_MULTITCE)) {
> +				printk(KERN_INFO "Disabling MULTITCE firmware feature\n");
> +				ppc_md.tce_build = tce_build_pSeriesLP;
> +				ppc_md.tce_free	 = tce_free_pSeriesLP;
> +				powerpc_firmware_features &= ~FW_FEATURE_MULTITCE;
> +			}
> +		}
> +	}

I personally prefer to keep cases like these in one if statement to save indentation:

	if (strcmp(str, "off") == 0 &&
	    firmware_has_feature(FW_FEATURE_LPAR) &&
	    firmware_has_feature(FW_FEATURE_MULTITCE)) {
		<...>
	}

> +	return 1;
> +}
> +
> +__setup("multitce=",disable_multitce);
> diff --git a/arch/powerpc/platforms/pseries/lpar.c b/arch/powerpc/platforms/pseries/lpar.c
> index 0707653..82d15e7 100644
> --- a/arch/powerpc/platforms/pseries/lpar.c
> +++ b/arch/powerpc/platforms/pseries/lpar.c
> @@ -599,6 +599,19 @@ static void pSeries_lpar_flush_hash_range(unsigned long number, int local)
>  		spin_unlock_irqrestore(&pSeries_lpar_tlbie_lock, flags);
>  }
>  
> +static int __init disable_bulk_remove(char *str)
> +{
> +	if (strcmp(str,"off")==0) {
> +		if (firmware_has_feature(FW_FEATURE_BULK_REMOVE)) {
> +			printk(KERN_INFO "Disabling BULK_REMOVE firmware feature");
> +			powerpc_firmware_features &= ~FW_FEATURE_BULK_REMOVE;
> +		}
> +	}

Same here.

> +	return 1;
> +}
> +
> +__setup("bulk_remove=",disable_bulk_remove);
> +
>  void __init hpte_init_lpar(void)
>  {
>  	ppc_md.hpte_invalidate	= pSeries_lpar_hpte_invalidate;
>

Patch

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index e2c7487..5c40801 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -426,6 +426,10 @@  and is between 256 and 4096 characters. It is defined in the file
 	bttv.pll=	See Documentation/video4linux/bttv/Insmod-options
 	bttv.tuner=	and Documentation/video4linux/bttv/CARDLIST
 
+	bulk_remove=off	[PPC]  This parameter disables the use of the pSeries
+			firmware feature for flushing multiple hpte entries
+			at a time.
+
 	BusLogic=	[HW,SCSI]
 			See drivers/scsi/BusLogic.c, comment before function
 			BusLogic_ParseDriverOptions().
@@ -1499,6 +1503,10 @@  and is between 256 and 4096 characters. It is defined in the file
 	mtdparts=	[MTD]
 			See drivers/mtd/cmdlinepart.c.
 
+	multitce=off	[PPC]  This parameter disables the use of the pSeries
+			firmware feature for updating multiple TCE entries
+			at a time.
+
 	onenand.bdry=	[HW,MTD] Flex-OneNAND Boundary Configuration
 
 			Format: [die0_boundary][,die0_lock][,die1_boundary][,die1_lock]
diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
index 902987d..e174a2f 100644
--- a/arch/powerpc/platforms/pseries/iommu.c
+++ b/arch/powerpc/platforms/pseries/iommu.c
@@ -625,3 +625,19 @@  void iommu_init_early_pSeries(void)
 	set_pci_dma_ops(&dma_iommu_ops);
 }
 
+static int __init disable_multitce(char *str)
+{
+	if (strcmp(str,"off")==0) {
+		if (firmware_has_feature(FW_FEATURE_LPAR)) {
+			if (firmware_has_feature(FW_FEATURE_MULTITCE)) {
+				printk(KERN_INFO "Disabling MULTITCE firmware feature\n");
+				ppc_md.tce_build = tce_build_pSeriesLP;
+				ppc_md.tce_free	 = tce_free_pSeriesLP;
+				powerpc_firmware_features &= ~FW_FEATURE_MULTITCE;
+			}
+		}
+	}
+	return 1;
+}
+
+__setup("multitce=",disable_multitce);
diff --git a/arch/powerpc/platforms/pseries/lpar.c b/arch/powerpc/platforms/pseries/lpar.c
index 0707653..82d15e7 100644
--- a/arch/powerpc/platforms/pseries/lpar.c
+++ b/arch/powerpc/platforms/pseries/lpar.c
@@ -599,6 +599,19 @@  static void pSeries_lpar_flush_hash_range(unsigned long number, int local)
 		spin_unlock_irqrestore(&pSeries_lpar_tlbie_lock, flags);
 }
 
+static int __init disable_bulk_remove(char *str)
+{
+	if (strcmp(str,"off")==0) {
+		if (firmware_has_feature(FW_FEATURE_BULK_REMOVE)) {
+			printk(KERN_INFO "Disabling BULK_REMOVE firmware feature");
+			powerpc_firmware_features &= ~FW_FEATURE_BULK_REMOVE;
+		}
+	}
+	return 1;
+}
+
+__setup("bulk_remove=",disable_bulk_remove);
+
 void __init hpte_init_lpar(void)
 {
 	ppc_md.hpte_invalidate	= pSeries_lpar_hpte_invalidate;