[v2] bitmap: add scan from offset function
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Commit Message
Currently, in the case when we search for a bit set after a particular
value, the bitmap has to be scanned from the beginning and
rte_bitmap_scan() has to be called multiple times until we hit the value.
Add a new rte_bitmap_scan_from_offset() function to initialize scan
state at the given offset and perform scan, this will allow getting
the next set bit after certain offset within one scan call.
Signed-off-by: Volodymyr Fialko <vfialko@marvell.com>
---
app/test/test_bitmap.c | 33 ++++++++++++++++++++-
lib/eal/include/rte_bitmap.h | 56 ++++++++++++++++++++++++++++++++++++
2 files changed, 88 insertions(+), 1 deletion(-)
Comments
> -----Original Message-----
> From: Volodymyr Fialko <vfialko@marvell.com>
> Sent: Tuesday, June 13, 2023 4:40 PM
> To: dev@dpdk.org; Dumitrescu, Cristian <cristian.dumitrescu@intel.com>
> Cc: jerinj@marvell.com; anoobj@marvell.com; thomas@monjalon.net;
> Volodymyr Fialko <vfialko@marvell.com>
> Subject: [PATCH v2] bitmap: add scan from offset function
>
> Currently, in the case when we search for a bit set after a particular
> value, the bitmap has to be scanned from the beginning and
> rte_bitmap_scan() has to be called multiple times until we hit the value.
>
> Add a new rte_bitmap_scan_from_offset() function to initialize scan
> state at the given offset and perform scan, this will allow getting
> the next set bit after certain offset within one scan call.
>
> Signed-off-by: Volodymyr Fialko <vfialko@marvell.com>
> ---
> app/test/test_bitmap.c | 33 ++++++++++++++++++++-
> lib/eal/include/rte_bitmap.h | 56 ++++++++++++++++++++++++++++++++++++
> 2 files changed, 88 insertions(+), 1 deletion(-)
>
<snip>
> +/**
> + * @warning
> + * @b EXPERIMENTAL: this API may change without prior notice.
> + *
> + * Bitmap initialize internal scan pointers at the given position for the scan
> function.
> + *
> + * @param bmp
> + * Handle to bitmap instance
> + * @param pos
> + * Bit position to start scan
> + */
> +__rte_experimental
> +static inline void
> +__rte_bitmap_scan_init_at(struct rte_bitmap *bmp, uint32_t pos)
Please add a note for this function to mark it as internal, which should be obvious from the double underscore prefix in the name, but better to write it explicitly as well.
@@ -18,8 +18,8 @@ test_bitmap_scan_operations(struct rte_bitmap *bmp)
{
uint64_t slab1_magic = 0xBADC0FFEEBADF00D;
uint64_t slab2_magic = 0xFEEDDEADDEADF00D;
+ int i, nb_clear, nb_set, next_cl;
uint32_t pos = 0, start_pos;
- int i, nb_clear, nb_set;
uint64_t out_slab = 0;
rte_bitmap_reset(bmp);
@@ -71,6 +71,37 @@ test_bitmap_scan_operations(struct rte_bitmap *bmp)
return TEST_FAILED;
}
+ /* Scan with offset check. */
+ if (!rte_bitmap_scan_from_offset(bmp, RTE_BITMAP_SLAB_BIT_SIZE, &pos, &out_slab)) {
+ printf("Failed to get slab from bitmap with scan from offset.\n");
+ return TEST_FAILED;
+ }
+
+ if (slab2_magic != out_slab) {
+ printf("Scan from offset operation failed.\n");
+ return TEST_FAILED;
+ }
+
+ /* Scan with offset wrap around check. */
+ if (!rte_bitmap_scan_from_offset(bmp, 2 * RTE_BITMAP_SLAB_BIT_SIZE, &pos, &out_slab)) {
+ printf("Failed to get slab from bitmap with scan from offset.\n");
+ return TEST_FAILED;
+ }
+
+ if (slab1_magic != out_slab) {
+ printf("Scan from offset with wrap around operation failed.\n");
+ return TEST_FAILED;
+ }
+
+ /* Test scan when the bit set is on a next cline */
+ rte_bitmap_reset(bmp);
+ next_cl = RTE_MIN(RTE_BITMAP_CL_BIT_SIZE, MAX_BITS);
+ rte_bitmap_set(bmp, next_cl);
+ if (!rte_bitmap_scan_from_offset(bmp, 0, &pos, &out_slab)) {
+ printf("Failed to get slab from next cache line from bitmap.\n");
+ return TEST_FAILED;
+ }
+
/* Test scan when a cline is half full */
rte_bitmap_reset(bmp);
for (i = 0; i < MAX_BITS; i++)
@@ -137,6 +137,30 @@ __rte_bitmap_scan_init(struct rte_bitmap *bmp)
bmp->go2 = 0;
}
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice.
+ *
+ * Bitmap initialize internal scan pointers at the given position for the scan function.
+ *
+ * @param bmp
+ * Handle to bitmap instance
+ * @param pos
+ * Bit position to start scan
+ */
+__rte_experimental
+static inline void
+__rte_bitmap_scan_init_at(struct rte_bitmap *bmp, uint32_t pos)
+{
+ uint64_t *slab1;
+
+ bmp->index1 = pos >> (RTE_BITMAP_SLAB_BIT_SIZE_LOG2 + RTE_BITMAP_CL_BIT_SIZE_LOG2);
+ bmp->offset1 = (pos >> RTE_BITMAP_CL_BIT_SIZE_LOG2) & RTE_BITMAP_SLAB_BIT_MASK;
+ bmp->index2 = pos >> RTE_BITMAP_SLAB_BIT_SIZE_LOG2;
+ slab1 = bmp->array1 + bmp->index1;
+ bmp->go2 = *slab1 & (1llu << bmp->offset1);
+}
+
/**
* Bitmap memory footprint calculation
*
@@ -591,6 +615,38 @@ rte_bitmap_scan(struct rte_bitmap *bmp, uint32_t *pos, uint64_t *slab)
return 0;
}
+/**
+ * @warning
+ * @b EXPERIMENTAL: this API may change without prior notice.
+ *
+ * Bitmap scan from the given offset.
+ * Function will reset internal scan state to start scanning from the offset
+ * position.
+ * @see rte_bitmap_scan()
+ *
+ * @param bmp
+ * Handle to bitmap instance
+ * @param offset
+ * Bit offset to start scan
+ * @param pos
+ * When function call returns 1, pos contains the position of the next set
+ * bit, otherwise not modified
+ * @param slab
+ * When function call returns 1, slab contains the value of the entire 64-bit
+ * slab where the bit indicated by pos is located.
+ * When function call returns 0, slab is not modified.
+ * @return
+ * 0 if there is no bit set in the bitmap, 1 otherwise
+ */
+__rte_experimental
+static inline int
+rte_bitmap_scan_from_offset(struct rte_bitmap *bmp, uint32_t offset,
+ uint32_t *pos, uint64_t *slab)
+{
+ __rte_bitmap_scan_init_at(bmp, offset);
+ return rte_bitmap_scan(bmp, pos, slab);
+}
+
#ifdef __cplusplus
}
#endif