A detailed comparison of Cortex-A53-based and other SoCs using Geekbench, and impact of AArch64

More Cortex-A53 CPU core-based SoCs have recently come to market and more benchmark results are now available, for example from the Geekbench results database. Firmware is also becoming more mature. This makes it possible to make better comparisons between different Cortex-A53-based SoCs (for example, octa-core SoCs) and compare the performance of the highest-performance chips with competitive chips that use more expensive CPU cores such as Krait 400 and Cortex-A57.

Overview of Cortex-A53-based SoCs

The following is a list of Cortex-A53 CPU core-based mobile SoCs that have appeared in the market or for which benchmark results have become available. All chips integrate 4G LTE modem functionality unless otherwise noted.

• Snapdragon 410 (MSM8916), utilizing four early Cortex-A53r0p0 cores. Numerous cost-sensitive smartphones now use this chip. However, none of them appears to take any advantage at all of the new ARMv8 instruction set, with all of them running in ARMv7 compatibility mode. This is counter-intuitive because AArch32 (32-bit version of ARMv8), which is used by the other SoCs, already brings significant benefits. Snapdragon 410 generally perform significantly worse than other Cortex-A53-based SoCs, even when correcting for the low clock speed. This is also reflected in memory performance. The Adreno 306 GPU tends to be even a little slower than the Adreno 305 GPU in Snapdragon 400. The net result is a chip that is not much faster than Snapdragon 400 in many cases while having worse battery life.

• Snapdragon 615 (MSM8939), equipped with an octa-core Cortex-A53r0p1 CPU configuration with four cores running (in practice) at 1.54 GHz or 1.50 GHz and four cores running at a lower maximum clock frequency (probably 1.0 GHz). This chip has appeared in an increasing number of new smartphone models. Runs in AArch32 mode. Performance is significantly lower than MediaTek's octa-core Cortex-A53-based SoCs, which can run all eight Cortex-A53 cores at the maximum frequency. Memory performance is improved from Snapdragon 410 but falls short of that of MediaTek's SoCs. The Adreno 405 GPU is fairly competitive, suitable for a mid-range SoC, although the 32-bit RAM interface of the SoC limits performance, especially at high resolutions. It is manufactured used TSMC's lower performance 28LP process. There have been reports that the chip gets hot with intensive use and requires throttling.

• MediaTek MT6732, with an quad-core Cortex-A53r0p2 CPU configuration running at a maximum clock speed of 1.5 GHz. Devices using the chip are starting to become available, and tablets with the tablet version of this chip (MT8732) have also been announced. Although it has only four CPU cores, it has good performance, beating Snapdragon 615 in single core performance at a similar clock speed, and memory performance is significantly higher. The Mali-T760 MP2 GPU contributes to better GPU performance than previous MediaTek chips targeting cost-sensitive segments, although falling short of that of Snapdragon 615 and MT6752. A tablet version of the chip exists as MT8732.

• MediaTek MT6752, featuring an octa-core Cortex-A53r0p2 CPU configuration with a maximum clock frequency of 1.69 GHz. Several devices have come to market using this chip, including the Meizu M1 Note. Performance is excellent, with high scores in the Geekbench CPU benchmark, considerably higher than Snapdragon 615 and beating high-end SoCs such as Snapdragon 801 in several metrics. The Mali-T760 MP2 GPU is clocked higher than that of the MT6732, resulting in good GPU performance, comparable to that of Snapdragon 615, as measured with GFXBench, although the 32-bit memory interface will be a bottleneck at high resolutions. Manufactured using TSMC's high-performance 28HPM process. A tablet version of the chip exists as MT8752.

• MediaTek MT6795, with an octa-core Cortex-A53r0p2 CPU with clock speed up to 2.16 GHz. With a dual-channel memory interface and high resolution support, this SoC targets a higher performance segment than the previously mentioned chips, for which it can potentially offer much better performance/dollar because of the small die size of Cortex-A53 cores. Originally announced as become available in commercial devices before the end of 2014, it was delayed but competitive benchmark scores for what appears to be more mature versions of the chip have recently shown up. It appears to be configured with full AArch64 mode. Performance is excellent, with single-core performance closing much of the gap with the high-end Snapdragon 801, while multi-core performance is significantly higher. There appears to be a "Turbo" version running the CPU up to 2.16 GHz, while the regular version clocks at 1.95 GHz. At the MWC on 2 March 2015, MediaTek apparently rebranded the MT6795 as Helio X10.

• MediaTek's MT6735 is a SoC for entry-level smartphones for which benchmark results have not yet become available. It has a quad-core Cortex-A53 CPU configuration and a Mali-T720 GPU, a downgrade from the Mali-T760 GPU in MT6732. The recently announced MT6753, with eight Cortex-A53 cores running up to 1.5 GHz, is compatible with the MT6735 and also has a Mali-T720 GPU (probably MP4). Other chips that have shown up in product announcements include the MT8161 (probably the equivalent of the MT6735 without modem) and MT8165 (equivalent to MT8732 without modem).

• Qualcomm has announced additional octa-core Cortex-A53-based chips, Snapdragon 415 and Snapdragon 425. These probably utilize symmetrical Cortex-A53 configuration with all cores running at the same maximum clock frequency, unlike Snapdragon 615. Otherwise, the new SoCs are similar to Snapdragon 615, with the same Adreno 405 GPU. According to Qualcomm, devices using these chips will become commercially available in the second half of 2015.

• Kirin 620 (Hi6210) from HiSilicon (Huawei) is an octa-core Cortex-A53r0p3-based SoC running up to 1.2 GHz. The GPU is a Mali-450 MP4. Although performance (including single-core performance) is better than Snapdragon 410, it is not as optimized as chips such as MT6752 and runs at a relatively low clock speed. Multi-core performance scaling is less than expected.

Geekbench integer and memory scores comparison

The following table provides details about selected Geekbench integer and memory benchmark scores for different Cortex-A53-based SoCs, and also other smartphone SoCs from Qualcomm, MediaTek and Samsung for comparison.

                Arch    Max freq. JPEG C. IPC   JPEG C. Dijkstra      Stream Copy   Geekbench
                                  Single  x A7  Multi   Single Multi  Single Multi  Ref. number

Snapdragon 410  ARMv7     1.19      596   1.30   2384     810   2135   431   492    1551964
Snapdragon 615  AArch32 1.50/1.0    820   1.42   4979     886   3646   572   703    2015694
MT6732          AArch32   1.50      843   1.46   3357    1041   3002  1001  1199    1546611
MT6752          AArch32   1.69      952   1.46   7554    1144   4483  1071  1191    1583540
MT6795          AArch64   1.95     1026   1.37   8167     990   3802  1356  2068    2002894
MT6795T         AArch64   2.16     1128   1.36   8962    1064   4109  1350  2140    1984431
Hi6210          AArch32   1.20      660   1.43   3501     744   2772   602   900    1999304

Snapdragon 400  ARMv7     1.19      462   1.01   1860     700   2132   534   551    1938063
Snapdragon 801  ARMv7     2.46     1347   1.42   5437    1174   3586  1931  2144    1491681
Snapdragon 805  ARMv7     2.65     1475   1.45   4105    1230   4058  2117  2910    1502687
Snapdragon 810  AArch64  ?/1.55    1358          5972    1073   3584  1428  1838    2017257
MT6582          ARMv7     1.30      506   1.01   2027     748   2354   250   396    2017732
MT6592          ARMv7     1.66      643   1.01   5086     891   3327   261   388    2000008
MT6595          ARMv7   2.20/1.69  1350   1.59   6080    1844   5612  1652  1986    1591744
Exynos 5430     ARMv7   1.80/1.3   1056   1.52   5140    1102   3918  1457  1559    1556780
Exynos 5433     AArch32   1.89     1456   2.10   6209    1523   5728  1396  1458    2017193
Exynos 7420     AArch64  ?/1.50    1481          7168    1065   4596  1953  2579    2012972

The low performance of Snapdragon 410 is apparent in the scores, with normalized IPC (instructions per cycle to the equivalent of a 1.0 GHz Cortex-A7) for the CPU-speed sensitive single-core JPEG Compress benchmark being lower than that of other Cortex-A53-based SoCs, probably due to being limited to ARMv7. The Dijkstra benchmark even scores lower on Snapdragon 410 than on an equivalently clocked Snapdragon 400, and memory performance is also lower.

Snapdragon 615, while improving on Snapdragon 410, also appears to be less optimized than MT6732/MT6752 in terms of single-core IPC, despite a very similar clock frequency. Looking at multi-core performance, MT6752 is significantly faster than Snapdragon 615, largely due to being able run all eight cores at the maximum clock frequency. MT6732 and MT6752 also have significantly higher memory performance, reaching an impressive score for devices with a 32-bit memory interface.

The higher clock speed of MT6795 (Helio X10) brings benefits for integer performance, but due to the use of the AArch64 instruction set, normalized IPC is lower (1.36 vs 1.46 for JPEG Compress). This is especially true for the Dijkstra benchmark, where AArch64 mode imposes a significant penalty (this is also seen on other platforms utilizing AArch64).

Overall, a high-speed Cortex-A53 configuration such as implemented in the MT6795T comes fairly close to Snapdragon 801 for single-core performance, while being significantly faster for multi-core performance, at a significantly lower cost. Several metrics are also in the same ballpark as the current high-end leader Exynos 7420.

Analysis of the Geekbench Lua subtest

The Lua integer benchmark appears to be particularly sensitive to memory subsystem efficiency, including L2 cache size, and memory bandwidth as well being dependent on CPU speed. It is the kind of code that may frequently occur in actual practice on a smartphone.

                Arch      Lua     IPC   Lua    CPU    #CPUs
                          Single  x A7  Multi  Par.

Snapdragon 410  ARMv7      603    1.23  2137   3.54   4
Snapdragon 615  AArch32    709    1.15  1644   2.32   4 + 4
MT6732          AArch32    753    1.22  2419   3.21   4
MT6752          AArch32    842    1.21  2361   2.80   8
MT6795          AArch64   1053    1.31  8203   7.79   8
MT6795T         AArch64   1173    1.32  8847   7.54   8
Hi6210          AArch32    587    1.19  1740   2.96   8

Snapdragon 400  ARMv7      476    0.97  1874   3.94   4
Snapdragon 801  ARMv7      980    0.97  2880   2.94   4
Snapdragon 805  ARMv7     1016    0.93  2917   2.87   4
Snapdragon 810  AArch64   1283          1065   0.83   4 + 4
MT6582          ARMv7      514    0.96  1644   3.20   4
MT6592          ARMv7      651    0.95  1344   2.06   8
MT6595          ARMv7     1509    1.67  2498   1.66   4 + 4
Exynos 5430     ARMv7      981    1.33  1861   1.90   4 + 4
Exynos 5433     AArch32   1397    1.89  5478   3.92   4 + 4
Exynos 7420     AArch64   1409          7088   5.03   4 + 4

In this test, Snapdragon 410 performs reasonably well. MT6752's multi-core performance seems limited by a bottleneck, probably external memory bandwidth. MT6795's performance is impressive; while single-core performance falls a little short of Cortex-A57 based SoCs, for multi-core performance it blows past them, with CPU parallelism fully exploited. It seems the bottleneck present with the MT6752 (presumably memory bandwidth and the L2 cache memory size available to each core) is not present with the MT6795.

Qualcomm's Snapdragon 810 consistently scores in the 1000-1200 range for both the single-core and multi-core test, while the multi-core test would have been expected to be significantly higher. This appears to reflect a serious deficiency in the memory subsystem of the SoC (which might not only be related tot the LPDDR4 SDRAM controller, but also the on-chip L2 cache) which might also have negative implications for smoothness in every-day use.

Geekbench floating points subtests

Finally, let's look at floating point performance. The Mandelbrot subtest tests pure floating point performance, while the SGEMM and SFFT tests also significantly depend on memory performance.

                Arch      Mandelbrot                 SGEMM         SFFT
                          Single  IPC   Multi  Par.  Single Multi  Single Multi

Snapdragon 410  ARMv7      448    1.10  1794   4.00   245    489    317   1258
Snapdragon 615  AArch32    583    1.14  3611   6.19   303    688    426   2517
MT6732          AArch32    585    1.14  2336   3.99   337    653    430   1727
MT6752          AArch32    661    1.15  5257   7.95   384   1148    481   3870
MT6795          AArch64    823    1.24  6406   7.78   484   1542    618   4764
MT6795T         AArch64    912    1.24  7245   7.94   529   1659    694   5333
Hi6210          AArch32    467    1.14  3509   7.51   264    876    343   2178

Snapdragon 400  ARMv7      405    1.00  1620   4.00   203    634    285   1182
Snapdragon 801  ARMv7      788    0.94  3104   3.94   907   2816    992   3518
Snapdragon 805  ARMv7      848    0.94  3389   4.00  1011   2669   1130   4135
Snapdragon 810  AArch64   1100          5144   4.68   749   1828   1009   3643
MT6582          ARMv7      444    1.00  1765   3.98   230    512    328   1316
MT6592          ARMv7      568    1.00  4430   7.80   282    696    419   3397
MT6595          ARMv7     1284    1.71  5822   4.53   748   2337   1187   4255
Exynos 5430     ARMv7      990    1.61  4745   4.79   657   2491    896   3971
Exynos 5433     AArch32   1174    1.91  4883   4.16   751   2369   1044   4031
Exynos 7420     AArch64   1198          6129   5.12   945   2888   1313   4874

From these numbers its is clear that Cortex-A53 improves floating point performance somewhat when compared to Cortex-A7 at the same clock speed. When eight cores can run in parallel at high speed, multi-core floating point performance is impressive, as demonstrated by MT6752 and MT6795. Snapdragon 801 and 805 are looking a bit dated in this department.

In the memory-intensive SGEMM and SFFT tests, Snapdragon 400 comes close to Snapdragon 410, illustrating the lack of performance improvement by Snapdragon 410. In fact MediaTek's previous generation MT6582 matches the floating point performance of Snapdragon 410 across all tests.

The Cortex-A57 based SoCs have the highest single-core floating point performance, although the Cortex-A17-based MT6595 is also very strong. Exynos 5433 and Exynos 7420 beat Snapdragon 810 in most floating point tests, although the difference is not as large as it used to be with earlier results for Snapdragon 810.

Conclusion

It is clear that octa-core Cortex-A53-based SoCs can deliver strong performance at a relatively low cost, and this particularly true for MediaTek's new chips, MT6752 and MT6795. The MT6795, with its higher clock speed and dual-channel memory interface, can match current high-end chips in most metrics, being not much slower in single-core performance while being superior in multi-core.

One unknown question is whether the high maximum clock frequency of the MT6795 and MT6795T, which deliver impressive performance/dollar, translates to acceptable power consumption and battery life. Observations that power consumption for Cortex-A53 can quickly increase at higher frequencies for the Samsung-manufactured Exynos 5433 have been made, but MT6795 is manufactured on different process at TSMC and probably makes use of specific design optimizations for high clock speeds (ARM POP IP core hardening technology) that make power consumption more acceptable.

Sources: Geekbench Browser

Updated 10 March 2015.