Herbert, Thanks for your suggestion to flush the jobs when cpu goes to idle. I've updated the code to flush the unfinished jobs in the lanes when the cpu goes to idle, to take advantage of the available cpu cycles for processing. This should minimize any latency for the multi-buffer algorithm. It adds a bit of overhead to the idle path to check for unfinished jobs. Any suggestions to optimize this will be welcomed. In this patch series, we introduce the multi-buffer crypto algorithm on x86_64 and apply it to SHA1 hash computation. The multi-buffer technique takes advantage of the 8 data lanes in the AVX2 registers and allows computation to be performed on data from multiple jobs in parallel. This allows us to parallelize computations when data inter-dependency in a single crypto job prevents us to fully parallelize our computations. The algorithm can be extended to other hashing and encryption schemes in the future. On multi-buffer SHA1 computation with AVX2, we see throughput increase up to 2.2x over the existing x86_64 single buffer AVX2 algorithm. The multi-buffer crypto algorithm is described in the following paper: Processing Multiple Buffers in Parallel to Increase Performance on Intel® Architecture Processors http://www.intel.com/content/www/us/en/communications/communications-ia-multi-buffer-paper.html The outline of the algorithm is sketched below: Any driver requesting the crypto service will place an async crypto request on the workqueue. The multi-buffer crypto daemon will pull request from work queue and put each request in an empty data lane for multi-buffer crypto computation. When all the empty lanes are filled, computation will commence on the jobs in parallel and the job with the shortest remaining buffer will get completed and be returned. To prevent prolonged stall when there is no new jobs arriving, we will flush a crypto job if it has not been completed after a maximum allowable delay, or when cpu becomes idle and cpu cycles become available. The multi-buffer algorithm necessitates mapping multiple scatter gather buffers to linear addresses simultaneously. The crypto daemon may need to sleep and yield the cpu to work on something else from time to time. We made a change to not use kmap_atomic to do scatter-gather buffer mapping and take advantage of the fact that we can directly translate address the buffer's address to its linear address with x86_64. To accommodate the fragmented nature of scatter-gather, we will keep submitting the next scatter-buffer fragment for a job for multi-buffer computation until a job is completed and no more buffer fragments remain. At that time we will pull a new job to fill the now empty data slot. We call a get_completed_job function to check whether there are other jobs that have been completed when we job when we have no new job arrival to prevent extraneous delay in returning any completed jobs. The multi-buffer algorithm should be used for cases where crypto jobs submissions are at a reasonable high rate. For low crypto job submission rate, this algorithm will not be beneficial. The reason is at low rate, we do not fill out the data lanes before flushing the jobs instead of processing them with all the data lanes full. We will miss the benefit of parallel computation, and adding delay to the processing of the crypto job at the same time. Some tuning of the maximum latency parameter may be needed to get the best performance. Note that the tcrypt SHA1 speed test, we wait for a previous job to be completed before submitting a new job. Hence this is not a valid test for multi-buffer algorithm as it requires multiple outstanding jobs submitted to fill the all data lanes to be effective (i.e. 8 outstanding jobs for the AVX2 case). Feedbacks and testings will be most welcomed. Tim Chen Change log: v3 1. Add notifier to multi-buffer algorithm to flush job when the cpu goes to idle to take advantage of available cpu cycles. 2. Clean up of error messages. v2 1. Change the sha1 crypto walk to use the new crypto_ahash_walk interface for proper kmap. 2. Drop the hack that map buffer in crypto_hash_walk without kmap_atomic as the new crypto_ahash_walk interface is merged. 3. Reorganize some of the mcryptd hash interface code from ahash.c to mcryptd.c v1 refer to : http://www.spinics.net/lists/linux-crypto/msg10993.html Tim Chen (6): crypto: SHA1 multibuffer crypto hash infrastructure crypto: SHA1 multibuffer algorithm data structures crypto: SHA1 multibuffer submit and flush routines for AVX2 crypto: SHA1 multibuffer crypto computation (x8 AVX2) crypto: SHA1 multibuffer scheduler crypto: SHA1 multibuffer - flush the jobs before going into idle arch/x86/crypto/Makefile | 2 + arch/x86/crypto/sha-mb/Makefile | 11 + arch/x86/crypto/sha-mb/sha1_mb.c | 990 +++++++++++++++++++++++ arch/x86/crypto/sha-mb/sha1_mb_mgr_datastruct.S | 287 +++++++ arch/x86/crypto/sha-mb/sha1_mb_mgr_flush_avx2.S | 327 ++++++++ arch/x86/crypto/sha-mb/sha1_mb_mgr_init_avx2.c | 64 ++ arch/x86/crypto/sha-mb/sha1_mb_mgr_submit_avx2.S | 228 ++++++ arch/x86/crypto/sha-mb/sha1_x8_avx2.S | 472 +++++++++++ arch/x86/crypto/sha-mb/sha_mb_ctx.h | 136 ++++ arch/x86/crypto/sha-mb/sha_mb_mgr.h | 110 +++ crypto/Kconfig | 30 + crypto/Makefile | 1 + crypto/mcryptd.c | 610 ++++++++++++++ crypto/shash.c | 12 + include/crypto/internal/hash.h | 9 + include/crypto/mcryptd.h | 109 +++ 16 files changed, 3398 insertions(+) create mode 100644 arch/x86/crypto/sha-mb/Makefile create mode 100644 arch/x86/crypto/sha-mb/sha1_mb.c create mode 100644 arch/x86/crypto/sha-mb/sha1_mb_mgr_datastruct.S create mode 100644 arch/x86/crypto/sha-mb/sha1_mb_mgr_flush_avx2.S create mode 100644 arch/x86/crypto/sha-mb/sha1_mb_mgr_init_avx2.c create mode 100644 arch/x86/crypto/sha-mb/sha1_mb_mgr_submit_avx2.S create mode 100644 arch/x86/crypto/sha-mb/sha1_x8_avx2.S create mode 100644 arch/x86/crypto/sha-mb/sha_mb_ctx.h create mode 100644 arch/x86/crypto/sha-mb/sha_mb_mgr.h create mode 100644 crypto/mcryptd.c create mode 100644 include/crypto/mcryptd.h -- 1.7.11.7 -- To unsubscribe from this list: send the line "unsubscribe linux-crypto" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
