diff mbox

[dpdk-dev] Fix power_of_2 macro. Avoid branching when calculating RTE_MIN and RTE_MAX.

Message ID CAFb4SLChYjhBGS4gnvfTGh-fqKTD7igFbwXdEypW7A=NMaQSdA@mail.gmail.com (mailing list archive)
State Superseded, archived
Headers

Commit Message

Ravi Kerur Dec. 9, 2014, 9:05 p.m. UTC 
Subject: [PATCH] Fix power_of_2 macro. Avoid branching when
calculating RTE_MIN and RTE_MAX.

---
 lib/librte_eal/common/include/rte_common.h | 6 +++---
 lib/librte_pmd_e1000/igb_pf.c              | 4 ++--
 lib/librte_pmd_ixgbe/ixgbe_pf.c            | 4 ++--
 3 files changed, 7 insertions(+), 7 deletions(-)

        uint32_t mta_idx;
@@ -399,7 +399,7 @@ ixgbe_vf_set_multicast(struct rte_eth_dev *dev,
__rte_unused uint32_t vf, uint32
        const uint32_t IXGBE_MTA_BIT_SHIFT = 5;
        const uint32_t IXGBE_MTA_BIT_MASK = (0x1 << IXGBE_MTA_BIT_SHIFT) - 1;
        uint32_t reg_val;
-       int i;
+       int16_t i;

        /* only so many hash values supported */
        nb_entries = RTE_MIN(nb_entries, IXGBE_MAX_VF_MC_ENTRIES);
--
1.9.1

Comments

Thomas Monjalon Dec. 10, 2014, 12:58 p.m. UTC | #1 
2014-12-09 13:05, r k:
> Subject: [PATCH] Fix power_of_2 macro. Avoid branching when
> calculating RTE_MIN and RTE_MAX.

Please could you add more explanations about the problem you are solving?

You should also add a Signed-off like explained in this page:
	http://dpdk.org/dev#send

Thanks
Ravi Kerur Dec. 10, 2014, 4:48 p.m. UTC | #2 
Just sent another patch explaining the fix and signed-off.

Thanks,
Ravi

On Wed, Dec 10, 2014 at 4:58 AM, Thomas Monjalon
<thomas.monjalon@6wind.com> wrote:
> 2014-12-09 13:05, r k:
>> Subject: [PATCH] Fix power_of_2 macro. Avoid branching when
>> calculating RTE_MIN and RTE_MAX.
>
> Please could you add more explanations about the problem you are solving?
>
> You should also add a Signed-off like explained in this page:
>         http://dpdk.org/dev#send
>
> Thanks
> --
> Thomas
diff mbox

Patch

diff --git a/lib/librte_eal/common/include/rte_common.h
b/lib/librte_eal/common/include/rte_common.h
index 921b91f..21b17ad 100644
--- a/lib/librte_eal/common/include/rte_common.h
+++ b/lib/librte_eal/common/include/rte_common.h
@@ -203,7 +203,7 @@  extern int RTE_BUILD_BUG_ON_detected_error;
static inline int  rte_is_power_of_2(uint32_t n)  {
-       return ((n-1) & n) == 0;
+       return n && !(n & (n - 1));
 }

 /**
@@ -259,7 +259,7 @@  rte_align64pow2(uint64_t v)  #define RTE_MIN(a, b) ({ \
                typeof (a) _a = (a); \
                typeof (b) _b = (b); \
-               _a < _b ? _a : _b; \
+                _b ^ ((_a ^ _b) & -(_a < _b)); \
        })

 /**
@@ -268,7 +268,7 @@  rte_align64pow2(uint64_t v)  #define RTE_MAX(a, b) ({ \
                typeof (a) _a = (a); \
                typeof (b) _b = (b); \
-               _a > _b ? _a : _b; \
+                _a ^ ((_a ^ _b) & -(_a < _b)); \
        })

 /*********** Other general functions / macros ********/ diff --git
a/lib/librte_pmd_e1000/igb_pf.c b/lib/librte_pmd_e1000/igb_pf.c index
bc3816a..546499c 100644
--- a/lib/librte_pmd_e1000/igb_pf.c
+++ b/lib/librte_pmd_e1000/igb_pf.c
@@ -321,11 +321,11 @@  igb_vf_set_mac_addr(struct rte_eth_dev *dev,
uint32_t vf, uint32_t *msgbuf)  static int
igb_vf_set_multicast(struct rte_eth_dev *dev, __rte_unused uint32_t
vf, uint32_t *msgbuf)  {
-       int i;
+       int16_t i;
        uint32_t vector_bit;
        uint32_t vector_reg;
        uint32_t mta_reg;
-       int entries = (msgbuf[0] & E1000_VT_MSGINFO_MASK) >>
+       int32_t entries = (msgbuf[0] & E1000_VT_MSGINFO_MASK) >>
                E1000_VT_MSGINFO_SHIFT;
        uint16_t *hash_list = (uint16_t *)&msgbuf[1];
        struct e1000_hw *hw = E1000_DEV_PRIVATE_TO_HW(dev->data->dev_private);
diff --git a/lib/librte_pmd_ixgbe/ixgbe_pf.c
b/lib/librte_pmd_ixgbe/ixgbe_pf.c index 51da1fd..426caf9 100644
--- a/lib/librte_pmd_ixgbe/ixgbe_pf.c
+++ b/lib/librte_pmd_ixgbe/ixgbe_pf.c
@@ -390,7 +390,7 @@  ixgbe_vf_set_multicast(struct rte_eth_dev *dev,
__rte_unused uint32_t vf, uint32
        struct ixgbe_hw *hw = IXGBE_DEV_PRIVATE_TO_HW(dev->data->dev_private);
        struct ixgbe_vf_info *vfinfo =
                *(IXGBE_DEV_PRIVATE_TO_P_VFDATA(dev->data->dev_private));
-       int nb_entries = (msgbuf[0] & IXGBE_VT_MSGINFO_MASK) >>
+       int32_t nb_entries = (msgbuf[0] & IXGBE_VT_MSGINFO_MASK) >>
                IXGBE_VT_MSGINFO_SHIFT;
        uint16_t *hash_list = (uint16_t *)&msgbuf[1];