[dpdk-dev] [PATCH] drivers: cleanup unnecessary global variables
Pavan Nikhilesh
pbhagavatula at caviumnetworks.com
Wed Apr 25 17:52:00 CEST 2018
On Mon, Apr 23, 2018 at 11:00:09AM +0200, Olivier Matz wrote:
> On Fri, Apr 20, 2018 at 12:21:59AM +0530, Pavan Nikhilesh wrote:
> > Signed-off-by: Pavan Nikhilesh <pbhagavatula at caviumnetworks.com>
> > ---
> > drivers/bus/dpaa/base/fman/netcfg_layer.c | 5 -----
> > drivers/bus/dpaa/base/qbman/bman_driver.c | 4 ++--
> > drivers/bus/dpaa/base/qbman/qman.c | 2 +-
> > drivers/bus/dpaa/base/qbman/qman_driver.c | 4 ++--
> > drivers/bus/dpaa/base/qbman/qman_priv.h | 1 -
> > drivers/bus/dpaa/dpaa_bus.c | 2 +-
> > drivers/bus/fslmc/qbman/qbman_portal.c | 3 +--
> > drivers/bus/fslmc/qbman/qbman_portal.h | 1 -
> > drivers/net/i40e/i40e_flow.c | 2 +-
> > drivers/net/qede/base/bcm_osal.c | 2 +-
> > drivers/raw/skeleton_rawdev/skeleton_rawdev.c | 2 +-
> > lib/librte_net/net_crc_neon.h | 4 ++--
> > 12 files changed, 12 insertions(+), 20 deletions(-)
>
> [...]
>
> > diff --git a/lib/librte_net/net_crc_neon.h b/lib/librte_net/net_crc_neon.h
> > index 63fa1d4a1..cb3da72ed 100644
> > --- a/lib/librte_net/net_crc_neon.h
> > +++ b/lib/librte_net/net_crc_neon.h
> > @@ -21,8 +21,8 @@ struct crc_pmull_ctx {
> > uint64x2_t rk7_rk8;
> > };
> >
> > -struct crc_pmull_ctx crc32_eth_pmull __rte_aligned(16);
> > -struct crc_pmull_ctx crc16_ccitt_pmull __rte_aligned(16);
> > +static struct crc_pmull_ctx crc32_eth_pmull __rte_aligned(16);
> > +static struct crc_pmull_ctx crc16_ccitt_pmull __rte_aligned(16);
> >
> > /**
>
> Not sure it will still work after that.
>
> From what I see, these global variables are initialized once in
> rte_net_crc_neon_init, and used as a const parameter in
> crc32_eth_calc_pmull().
>
> Changing them to static will create an instance of these variables for
> each included file, which is not what we want.
>
> I think that the proper way to solve it would be to add the definition
> in a new .c file, and only have a declaration in the .h.
>
>
Hi Olivier,
Thanks for the heads up, the second solution seems more viable and while
implementing it I faced few Issues. GCC doesnt suport const vector instructions
i.e. the following assignment throw as compiler error.
static const struct crc_pmull_ctx crc32_eth_pmull = {
.rk1_rk2 = vld1q_u64((uint64_t[2]){0xccaa009eLLU, 0x1751997d0LLU}),
.rk5_rk6 = vld1q_u64((uint64_t[2]){0xccaa009eLLU, 0x163cd6124LLU}),
.rk7_rk8 = vld1q_u64((uint64_t[2]){0x1f7011640LLU, 0x1db710641LLU}),
} __rte_aligned(16);
I have gotten path the error by modifying struct crc_pmull_ctx as follows:
struct crc_pmull_ctx {
union {
uint64_t rk12[2];
uint64x2_t rk1_rk2;
};
union {
uint64_t rk56[2];
uint64x2_t rk5_rk6;
};
union {
uint64_t rk78[2];
uint64x2_t rk7_rk8;
};
};
static const struct crc_pmull_ctx crc32_eth_pmull __rte_aligned(16) = {
.rk12 = {0xccaa009eLLU, 0x1751997d0LLU},
.rk56 = {0xccaa009eLLU, 0x163cd6124LLU},
.rk78 = {0x1f7011640LLU, 0x1db710641LLU},
};
static const struct crc_pmull_ctx crc16_ccitt_pmull __rte_aligned(16) = {
.rk12 = {0x189aeLLU, 0x8e10LLU},
.rk56 = {0x189aeLLU, 0x114aaLLU},
.rk78 = {0x11c581910LLU, 0x10811LLU},
};
I have checked the hex dump of the assignment with the current code and the
above piece of code and they are similar.
Let me know if my solution seems viable I will send the v2.
> An even better way would be to make variable const and initialize it
> with its content. It could even enhance performance. Something like:
>
> net_crc_neon.h:
>
> static const struct crc_pmull_ctx crc32_eth_pmull = {
> <values...>
> } __rte_aligned(16);
>
> static const struct crc_pmull_ctx crc16_ccitt_pmull = {
> <values...>
> } __rte_aligned(16);
>
Thanks,
Pavan.
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