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

[Zhang, Helin]

Hi Neil

> -----Original Message-----
> From: Neil Horman [mailto:nhorman at tuxdriver.com]
> Sent: Wednesday, December 24, 2014 10:55 PM
> To: Zhang, Helin
> Cc: dev at 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 at 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.

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
> >
> >