[dpdk-dev] [PATCH v2] mempool: fix slow allocation of large mempools
Olivier Matz
olivier.matz at 6wind.com
Fri Jan 17 10:51:49 CET 2020
When allocating a mempool which is larger than the largest
available area, it can take a lot of time:
a- the mempool calculate the required memory size, and tries
to allocate it, it fails
b- then it tries to allocate the largest available area (this
does not request new huge pages)
c- add this zone to the mempool, this triggers the allocation
of a mem hdr, which request a new huge page
d- back to a- until mempool is populated or until there is no
more memory
This can take a lot of time to finally fail (several minutes): in step
a- it takes all available hugepages on the system, then release them
after it fails.
The problem appeared with commit eba11e364614 ("mempool: reduce wasted
space on populate"), because smaller chunks are now allowed. Previously,
it had to be at least one page size, which is not the case in step b-.
To fix this, implement our own way to allocate the largest available
area instead of using the feature from memzone: if an allocation fails,
try to divide the size by 2 and retry. When the requested size falls
below min_chunk_size, stop and return an error.
Fixes: eba11e364614 ("mempool: reduce wasted space on populate")
Cc: stable at dpdk.org
Signed-off-by: Olivier Matz <olivier.matz at 6wind.com>
---
v2:
* fix missing check on mz == NULL condition
lib/librte_mempool/rte_mempool.c | 29 ++++++++++++-----------------
1 file changed, 12 insertions(+), 17 deletions(-)
diff --git a/lib/librte_mempool/rte_mempool.c b/lib/librte_mempool/rte_mempool.c
index 1eae10e27..a68a69040 100644
--- a/lib/librte_mempool/rte_mempool.c
+++ b/lib/librte_mempool/rte_mempool.c
@@ -499,6 +499,7 @@ rte_mempool_populate_default(struct rte_mempool *mp)
unsigned mz_id, n;
int ret;
bool need_iova_contig_obj;
+ size_t max_alloc_size = SIZE_MAX;
ret = mempool_ops_alloc_once(mp);
if (ret != 0)
@@ -578,30 +579,24 @@ rte_mempool_populate_default(struct rte_mempool *mp)
if (min_chunk_size == (size_t)mem_size)
mz_flags |= RTE_MEMZONE_IOVA_CONTIG;
- mz = rte_memzone_reserve_aligned(mz_name, mem_size,
+ /* Allocate a memzone, retrying with a smaller area on ENOMEM */
+ do {
+ mz = rte_memzone_reserve_aligned(mz_name,
+ RTE_MIN((size_t)mem_size, max_alloc_size),
mp->socket_id, mz_flags, align);
- /* don't try reserving with 0 size if we were asked to reserve
- * IOVA-contiguous memory.
- */
- if (min_chunk_size < (size_t)mem_size && mz == NULL) {
- /* not enough memory, retry with the biggest zone we
- * have
- */
- mz = rte_memzone_reserve_aligned(mz_name, 0,
- mp->socket_id, mz_flags, align);
- }
+ if (mz == NULL && rte_errno != ENOMEM)
+ break;
+
+ max_alloc_size = RTE_MIN(max_alloc_size,
+ (size_t)mem_size) / 2;
+ } while (mz == NULL && max_alloc_size >= min_chunk_size);
+
if (mz == NULL) {
ret = -rte_errno;
goto fail;
}
- if (mz->len < min_chunk_size) {
- rte_memzone_free(mz);
- ret = -ENOMEM;
- goto fail;
- }
-
if (need_iova_contig_obj)
iova = mz->iova;
else
--
2.20.1
More information about the dev
mailing list