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authorLEROY Christophe <christophe.leroy@c-s.fr>2017-10-06 15:05:06 +0200
committerHerbert Xu <herbert@gondor.apana.org.au>2017-10-12 22:55:38 +0800
commit37b5e8897eb588a60dada00c33d2dca8a7fec5fc (patch)
treefd0857a52821879b3cb3fca935072865139cc4dd /drivers/crypto/talitos.h
parent49f9783b0cea9a4e38fdbfe70ca296e6f20914c4 (diff)
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crypto: talitos - chain in buffered data for ahash on SEC1
SEC1 doesn't support S/G in descriptors so for hash operations, the CPU has to build a buffer containing the buffered block and the incoming data. This generates a lot of memory copies which represents more than 50% of CPU time of a md5sum operation as shown below with a 'perf record'. |--86.24%-- kcapi_md_digest | | | |--86.18%-- _kcapi_common_vmsplice_chunk_fd | | | | | |--83.68%-- splice | | | | | | | |--83.59%-- ret_from_syscall | | | | | | | | | |--83.52%-- sys_splice | | | | | | | | | | | |--83.49%-- splice_from_pipe | | | | | | | | | | | | | |--83.04%-- __splice_from_pipe | | | | | | | | | | | | | | | |--80.67%-- pipe_to_sendpage | | | | | | | | | | | | | | | | | |--78.25%-- hash_sendpage | | | | | | | | | | | | | | | | | | | |--60.08%-- ahash_process_req | | | | | | | | | | | | | | | | | | | | | |--56.36%-- sg_copy_buffer | | | | | | | | | | | | | | | | | | | | | | | |--55.29%-- memcpy | | | | | | | | | | | | However, unlike SEC2+, SEC1 offers the possibility to chain descriptors. It is therefore possible to build a first descriptor pointing to the buffered data and a second descriptor pointing to the incoming data, hence avoiding the memory copy to a single buffer. With this patch, the time necessary for a md5sum on a 90Mbytes file is approximately 3 seconds. Without the patch it takes 6 seconds. Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'drivers/crypto/talitos.h')
-rw-r--r--drivers/crypto/talitos.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/drivers/crypto/talitos.h b/drivers/crypto/talitos.h
index 2f04d83c3062..a65a63e0d6c1 100644
--- a/drivers/crypto/talitos.h
+++ b/drivers/crypto/talitos.h
@@ -236,6 +236,7 @@ static inline bool has_ftr_sec1(struct talitos_private *priv)
#define TALITOS_CCCR_LO_IWSE 0x80 /* chan. ICCR writeback enab. */
#define TALITOS_CCCR_LO_EAE 0x20 /* extended address enable */
#define TALITOS_CCCR_LO_CDWE 0x10 /* chan. done writeback enab. */
+#define TALITOS_CCCR_LO_NE 0x8 /* fetch next descriptor enab. */
#define TALITOS_CCCR_LO_NT 0x4 /* notification type */
#define TALITOS_CCCR_LO_CDIE 0x2 /* channel done IRQ enable */
#define TALITOS1_CCCR_LO_RESET 0x1 /* channel reset on SEC1 */