On Sat, Dec 25, 2021 at 01:16:03AM +0100, Morten Brørup wrote: > > From: Dharmik Thakkar [mailto:dharmik.thak...@arm.com] Sent: Friday, 24 > > December 2021 23.59 > > > > Current mempool per core cache implementation stores pointers to mbufs > > On 64b architectures, each pointer consumes 8B This patch replaces it > > with index-based implementation, where in each buffer is addressed by > > (pool base address + index) It reduces the amount of memory/cache > > required for per core cache > > > > L3Fwd performance testing reveals minor improvements in the cache > > performance (L1 and L2 misses reduced by 0.60%) with no change in > > throughput > > > > Micro-benchmarking the patch using mempool_perf_test shows significant > > improvement with majority of the test cases > > > > Number of cores = 1: n_get_bulk=1 n_put_bulk=1 n_keep=32 > > %_change_with_patch=18.01 n_get_bulk=1 n_put_bulk=1 n_keep=128 > > %_change_with_patch=19.91 n_get_bulk=1 n_put_bulk=4 n_keep=32 > > %_change_with_patch=-20.37 (regression) n_get_bulk=1 n_put_bulk=4 > > n_keep=128 %_change_with_patch=-17.01 (regression) n_get_bulk=1 > > n_put_bulk=32 n_keep=32 %_change_with_patch=-25.06 (regression) > > n_get_bulk=1 n_put_bulk=32 n_keep=128 %_change_with_patch=-23.81 > > (regression) n_get_bulk=4 n_put_bulk=1 n_keep=32 > > %_change_with_patch=53.93 n_get_bulk=4 n_put_bulk=1 n_keep=128 > > %_change_with_patch=60.90 n_get_bulk=4 n_put_bulk=4 n_keep=32 > > %_change_with_patch=1.64 n_get_bulk=4 n_put_bulk=4 n_keep=128 > > %_change_with_patch=8.76 n_get_bulk=4 n_put_bulk=32 n_keep=32 > > %_change_with_patch=-4.71 (regression) n_get_bulk=4 n_put_bulk=32 > > n_keep=128 %_change_with_patch=-3.19 (regression) n_get_bulk=32 > > n_put_bulk=1 n_keep=32 %_change_with_patch=65.63 n_get_bulk=32 > > n_put_bulk=1 n_keep=128 %_change_with_patch=75.19 n_get_bulk=32 > > n_put_bulk=4 n_keep=32 %_change_with_patch=11.75 n_get_bulk=32 > > n_put_bulk=4 n_keep=128 %_change_with_patch=15.52 n_get_bulk=32 > > n_put_bulk=32 n_keep=32 %_change_with_patch=13.45 n_get_bulk=32 > > n_put_bulk=32 n_keep=128 %_change_with_patch=11.58 > > > > Number of core = 2: n_get_bulk=1 n_put_bulk=1 n_keep=32 > > %_change_with_patch=18.21 n_get_bulk=1 n_put_bulk=1 n_keep=128 > > %_change_with_patch=21.89 n_get_bulk=1 n_put_bulk=4 n_keep=32 > > %_change_with_patch=-21.21 (regression) n_get_bulk=1 n_put_bulk=4 > > n_keep=128 %_change_with_patch=-17.05 (regression) n_get_bulk=1 > > n_put_bulk=32 n_keep=32 %_change_with_patch=-26.09 (regression) > > n_get_bulk=1 n_put_bulk=32 n_keep=128 %_change_with_patch=-23.49 > > (regression) n_get_bulk=4 n_put_bulk=1 n_keep=32 > > %_change_with_patch=56.28 n_get_bulk=4 n_put_bulk=1 n_keep=128 > > %_change_with_patch=67.69 n_get_bulk=4 n_put_bulk=4 n_keep=32 > > %_change_with_patch=1.45 n_get_bulk=4 n_put_bulk=4 n_keep=128 > > %_change_with_patch=8.84 n_get_bulk=4 n_put_bulk=32 n_keep=32 > > %_change_with_patch=-5.27 (regression) n_get_bulk=4 n_put_bulk=32 > > n_keep=128 %_change_with_patch=-3.09 (regression) n_get_bulk=32 > > n_put_bulk=1 n_keep=32 %_change_with_patch=76.11 n_get_bulk=32 > > n_put_bulk=1 n_keep=128 %_change_with_patch=86.06 n_get_bulk=32 > > n_put_bulk=4 n_keep=32 %_change_with_patch=11.86 n_get_bulk=32 > > n_put_bulk=4 n_keep=128 %_change_with_patch=16.55 n_get_bulk=32 > > n_put_bulk=32 n_keep=32 %_change_with_patch=13.01 n_get_bulk=32 > > n_put_bulk=32 n_keep=128 %_change_with_patch=11.51 > > > > > > From analyzing the results, it is clear that for n_get_bulk and > > n_put_bulk sizes of 32 there is no performance regression IMO, the > > other sizes are not practical from performance perspective and the > > regression in those cases can be safely ignored > > > > Dharmik Thakkar (1): mempool: implement index-based per core cache > > > > lib/mempool/rte_mempool.h | 114 +++++++++++++++++++++++++- > > lib/mempool/rte_mempool_ops_default.c | 7 ++ 2 files changed, 119 > > insertions(+), 2 deletions(-) > > > > -- 2.25.1 > > > > I still think this is very interesting. And your performance numbers are > looking good. > > However, it limits the size of a mempool to 4 GB. As previously > discussed, the max mempool size can be increased by multiplying the index > with a constant. > > I would suggest using sizeof(uintptr_t) as the constant multiplier, so > the mempool can hold objects of any size divisible by sizeof(uintptr_t). > And it would be silly to use a mempool to hold objects smaller than > sizeof(uintptr_t). > > How does the performance look if you multiply the index by > sizeof(uintptr_t)? >
Each mempool entry is cache aligned, so we can use that if we want a bigger multiplier.
