netdev - RE: [PATCH 1/8] ixgbe: Out of line ixgbe_read/write

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Message-ID: <063D6719AE5E284EB5DD2968C1650D6D17248D76@AcuExch.aculab.com>
Date:	Mon, 19 May 2014 09:14:57 +0000
From:	David Laight <David.Laight@...LAB.COM>
To:	'Andi Kleen' <andi@...stfloor.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	Andi Kleen <ak@...ux.intel.com>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"Jeff Kirsher" <jeffrey.t.kirsher@...el.com>
Subject: RE: [PATCH 1/8] ixgbe: Out of line ixgbe_read/write_reg

From: Andi Kleen
> ixgbe_read_reg and ixgbe_write_reg are frequently called and are very big
> because they have complex error handling code.

Have you measured the performance impact?
I suspect that it might me measurable.

Clearly the calls during initialisation don't need to be inline,
but there will be some in the normal tx and rx paths.

	David

> Moving them out of line saves ~27k text in the ixgbe driver.
> 
>    text	   data	    bss	    dec	    hex	filename
> 14220873	2008072	1507328	17736273	10ea251	vmlinux-before-ixgbe
> 14193673	2003976	1507328	17704977	10e2811	vmlinux-ixgbe
> 
> Cc: netdev@...r.kernel.org
> Cc: Jeff Kirsher <jeffrey.t.kirsher@...el.com>
> Signed-off-by: Andi Kleen <ak@...ux.intel.com>
> ---
>  drivers/net/ethernet/intel/ixgbe/ixgbe_common.h | 22 ++--------------------
>  drivers/net/ethernet/intel/ixgbe/ixgbe_main.c   | 22 ++++++++++++++++++++++
>  2 files changed, 24 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_common.h
> b/drivers/net/ethernet/intel/ixgbe/ixgbe_common.h
> index f12c40f..05f094d 100644
> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_common.h
> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_common.h
> @@ -162,28 +162,10 @@ static inline void writeq(u64 val, void __iomem *addr)
>  }
>  #endif
> 
> -static inline void ixgbe_write_reg64(struct ixgbe_hw *hw, u32 reg, u64 value)
> -{
> -	u8 __iomem *reg_addr = ACCESS_ONCE(hw->hw_addr);
> +void ixgbe_write_reg64(struct ixgbe_hw *hw, u32 reg, u64 value);
> +u32 ixgbe_read_reg(struct ixgbe_hw *hw, u32 reg);
> 
> -	if (ixgbe_removed(reg_addr))
> -		return;
> -	writeq(value, reg_addr + reg);
> -}
>  #define IXGBE_WRITE_REG64(a, reg, value) ixgbe_write_reg64((a), (reg), (value))
> -
> -static inline u32 ixgbe_read_reg(struct ixgbe_hw *hw, u32 reg)
> -{
> -	u8 __iomem *reg_addr = ACCESS_ONCE(hw->hw_addr);
> -	u32 value;
> -
> -	if (ixgbe_removed(reg_addr))
> -		return IXGBE_FAILED_READ_REG;
> -	value = readl(reg_addr + reg);
> -	if (unlikely(value == IXGBE_FAILED_READ_REG))
> -		ixgbe_check_remove(hw, reg);
> -	return value;
> -}
>  #define IXGBE_READ_REG(a, reg) ixgbe_read_reg((a), (reg))
> 
>  #define IXGBE_WRITE_REG_ARRAY(a, reg, offset, value) \
> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> index d62e7a2..5f81f62 100644
> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> @@ -371,6 +371,28 @@ void ixgbe_write_pci_cfg_word(struct ixgbe_hw *hw, u32 reg, u16 value)
>  	pci_write_config_word(adapter->pdev, reg, value);
>  }
> 
> +void ixgbe_write_reg64(struct ixgbe_hw *hw, u32 reg, u64 value)
> +{
> +	u8 __iomem *reg_addr = ACCESS_ONCE(hw->hw_addr);
> +
> +	if (ixgbe_removed(reg_addr))
> +		return;
> +	writeq(value, reg_addr + reg);
> +}
> +
> +u32 ixgbe_read_reg(struct ixgbe_hw *hw, u32 reg)
> +{
> +	u8 __iomem *reg_addr = ACCESS_ONCE(hw->hw_addr);
> +	u32 value;
> +
> +	if (ixgbe_removed(reg_addr))
> +		return IXGBE_FAILED_READ_REG;
> +	value = readl(reg_addr + reg);
> +	if (unlikely(value == IXGBE_FAILED_READ_REG))
> +		ixgbe_check_remove(hw, reg);
> +	return value;
> +}
> +
>  static void ixgbe_service_event_complete(struct ixgbe_adapter *adapter)
>  {
>  	BUG_ON(!test_bit(__IXGBE_SERVICE_SCHED, &adapter->state));
> --
> 1.9.0
> 
> --
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