Hi Suanming, > -----Original Message----- > From: Suanming Mou <suanmi...@mellanox.com> > Sent: Tuesday, March 10, 2020 8:21 AM > To: Dumitrescu, Cristian <cristian.dumitre...@intel.com> > Cc: dev@dpdk.org > Subject: [PATCH 1/2] bitmap: add create bitmap with all bits set > > Currently, in the case to use bitmap as resource allocator, after > bitmap creation, all the bitmap bits should be set to indicate the > bit available. Every time when allocate one bit, search for the set > bits and clear it to make it in use. > > Add a new rte_bitmap_init_with_all_set() function to have a quick > fill up the bitmap bits. > > Comparing with the case create the bitmap as empty and set the bitmap > one by one, the new function costs less cycles. > > Signed-off-by: Suanming Mou <suanmi...@mellanox.com> > --- > lib/librte_eal/common/include/rte_bitmap.h | 32 > ++++++++++++++++++++++++++++++ > 1 file changed, 32 insertions(+) > > diff --git a/lib/librte_eal/common/include/rte_bitmap.h > b/lib/librte_eal/common/include/rte_bitmap.h > index 6b846f2..36b32e4 100644 > --- a/lib/librte_eal/common/include/rte_bitmap.h > +++ b/lib/librte_eal/common/include/rte_bitmap.h > @@ -483,6 +483,38 @@ struct rte_bitmap { > return 0; > } > > +/** > + * Bitmap initialization with all bits set > + * > + * @param n_bits > + * Number of pre-allocated bits in array2. > + * @param mem > + * Base address of array1 and array2. > + * @param mem_size > + * Minimum expected size of bitmap. > + * @return > + * Handle to bitmap instance. > + */ > +static inline struct rte_bitmap * > +rte_bitmap_init_with_all_set(uint32_t n_bits, uint8_t *mem, uint32_t > mem_size) > +{ > + uint32_t i; > + uint32_t slabs = n_bits / RTE_BITMAP_SLAB_BIT_SIZE; > + struct rte_bitmap *bmp = rte_bitmap_init(n_bits, mem, mem_size); > + > + if (!bmp) > + return NULL; > + /* Fill the arry2 byte aligned bits. */ > + memset(bmp->array2, 0xff, slabs * sizeof(bmp->array2[0])); > + /* Fill the arry1 bits. */ > + for (i = 0; i < n_bits; i += RTE_BITMAP_CL_BIT_SIZE) > + rte_bitmap_set(bmp, i); > + /* Fill the arry2 left not byte aligned bits. */ > + for (i = slabs * RTE_BITMAP_SLAB_BIT_SIZE; i < n_bits; i++) > + rte_bitmap_set(bmp, i); > + return bmp; > +} > + > #ifdef __cplusplus > } > #endif > -- > 1.8.3.1
I agree that starting with all bits set could be very useful for some apps. I agree that having a customized implementation for starting with all bits set -- as opposed to simply start with all bits cleared and calling the API in a loop to set each bit -- could be useful, as it could reduce the initialization time. What I don't understand is your implementation of it: why still calling the API to set all bits in a loop? If we are to add this, I suggest we create a fully customized implementation that sets the fields on struct rte_bitmap to the right values. Makes sense? Thanks, Cristian