Re: [dpdk-dev] [PATCH] i40e: workaround for XL710 performance

[Neil Horman <nhorman@tuxdriver.com>]

On Thu, Dec 25, 2014 at 12:20:11AM +0000, Zhang, Helin wrote:
> Hi Neil
> 
> > -----Original Message-----
> > From: Neil Horman [mailto:nhorman@tuxdriver.com]
> > Sent: Wednesday, December 24, 2014 10:55 PM
> > To: Zhang, Helin
> > Cc: dev@dpdk.org
> > Subject: Re: [dpdk-dev] [PATCH] i40e: workaround for XL710 performance
> > 
> > On Wed, Dec 24, 2014 at 03:14:08PM +0800, Helin Zhang wrote:
> > > on XL710, performance number is far from the expectation on recent
> > > firmware versions, if promiscuous mode is disabled, or promiscuous
> > > mode is enabled and port MAC address is equal to the packet
> > > destination MAC address. The fix for this issue may not be integrated
> > > in the following firmware version. So the workaround in software
> > > driver is needed. It needs to modify the initial values of 2 internal
> > > only registers which is the same 2 of 3 registers of it did for X710.
> > > Note that the workaround can be removed when it is fixed in firmware
> > > in the future.
> > >
> > > Signed-off-by: Helin Zhang <helin.zhang@intel.com>
> > > ---
> > >  lib/librte_pmd_i40e/i40e_ethdev.c | 35
> > > ++++++++++++++++++++++-------------
> > >  1 file changed, 22 insertions(+), 13 deletions(-)
> > >
> > > diff --git a/lib/librte_pmd_i40e/i40e_ethdev.c
> > > b/lib/librte_pmd_i40e/i40e_ethdev.c
> > > index b47a3d2..3bb75d8 100644
> > > --- a/lib/librte_pmd_i40e/i40e_ethdev.c
> > > +++ b/lib/librte_pmd_i40e/i40e_ethdev.c
> > > @@ -5327,21 +5327,30 @@ i40e_debug_read_register(struct i40e_hw *hw,
> > > uint32_t addr, uint64_t *val)
> > >
> > >  /*
> > >   * On X710, performance number is far from the expectation on recent
> > > firmware
> > > - * versions. The fix for this issue may not be integrated in the
> > > following
> > > + * versions; on XL710, performance number is also far from the
> > > + expectation on
> > > + * recent firmware versions, if promiscuous mode is disabled, or
> > > + promiscuous
> > > + * mode is enabled and port MAC address is equal to the packet
> > > + destination MAC
> > > + * address. The fix for this issue may not be integrated in the
> > > + following
> > >   * firmware version. So the workaround in software driver is needed.
> > > It needs
> > > - * to modify the initial values of 3 internal only registers. Note
> > > that the
> > > - * workaround can be removed when it is fixed in firmware in the future.
> > > + * to modify the initial values of 3 internal only registers for
> > > + X710, and the
> > > + * same 2 internal registers for XL710. Note that the workaround can
> > > + be removed
> > > + * when it is fixed in firmware in the future.
> > 
> > Wouldn't it be preferable to add a firmware version check to this code so that a
> > single driver can handle both cards with old and 'fixed' firmware?  That way
> > nothing needs to be removed and all i40e cards will have a consistent behavior
> > Neil
> Yes, good idea!
> The problem is that no firmware contains this fix till now, firmware guys even
> cannot tell me which version will have this fix at this moment.
> As it reads the registers first, and compares if it is what we wanted, and then
> decides if a write is needed or not. With this, removing this piece of code is not
> actually needed even a fix occur in the future, though the code will be redundant.
> 
Very well, lets just make sure when it is fixed, the driver works with both
patched and unpatched firmware
Acked-by: Neil Horman <nhorman@tuxdriver.com>

> Thank you for the comments!
> 
> Regards,
> Helin
> 
> > 
> > >   */
> > > -static void
> > > -i40e_configure_registers(struct i40e_hw *hw) -{
> > > -#define I40E_GL_SWR_PRI_JOIN_MAP_0       0x26CE00
> > > -#define I40E_GL_SWR_PRI_JOIN_MAP_2       0x26CE08
> > > -#define I40E_GL_SWR_PM_UP_THR            0x269FBC
> > > +
> > > +/* For both X710 and XL710 */
> > >  #define I40E_GL_SWR_PRI_JOIN_MAP_0_VALUE 0x10000200
> > > +#define I40E_GL_SWR_PRI_JOIN_MAP_0       0x26CE00
> > > +
> > >  #define I40E_GL_SWR_PRI_JOIN_MAP_2_VALUE 0x011f0200
> > > +#define I40E_GL_SWR_PRI_JOIN_MAP_2       0x26CE08
> > > +
> > > +/* For X710 only */
> > >  #define I40E_GL_SWR_PM_UP_THR_VALUE      0x03030303
> > > +#define I40E_GL_SWR_PM_UP_THR            0x269FBC
> > >
> > > +static void
> > > +i40e_configure_registers(struct i40e_hw *hw) {
> > >  	static const struct {
> > >  		uint32_t addr;
> > >  		uint64_t val;
> > > @@ -5354,11 +5363,11 @@ i40e_configure_registers(struct i40e_hw *hw)
> > >  	uint32_t i;
> > >  	int ret;
> > >
> > > -	/* Below fix is for X710 only */
> > > -	if (i40e_is_40G_device(hw->device_id))
> > > -		return;
> > > -
> > >  	for (i = 0; i < RTE_DIM(reg_table); i++) {
> > > +		if ((i40e_is_40G_device(hw->device_id)) &&
> > > +			(reg_table[i].addr == I40E_GL_SWR_PM_UP_THR))
> > > +			continue;
> > > +
> > >  		ret = i40e_debug_read_register(hw, reg_table[i].addr, &reg);
> > >  		if (ret < 0) {
> > >  			PMD_DRV_LOG(ERR, "Failed to read from 0x%"PRIx32,
> > > --
> > > 1.9.3
> > >
> > >
>