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Date:   Mon, 16 Oct 2023 13:26:47 +0200 (CEST)
From:   Mikulas Patocka <mpatocka@redhat.com>
To:     Herbert Xu <herbert@gondor.apana.org.au>,
        "David S. Miller" <davem@davemloft.net>,
        Giovanni Cabiddu <giovanni.cabiddu@intel.com>
cc:     linux-crypto@vger.kernel.org, qat-linux@intel.com
Subject: [RFC PATCH] crypto: de-prioritize QAT
Message-ID: <0171515-7267-624-5a22-238af829698f@redhat.com>
MIME-Version: 1.0
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Hi

I created this kernel module that stress-tests the crypto API:
https://people.redhat.com/~mpatocka/benchmarks/qat/tools/module-multithreaded.c

It shows that QAT underperforms significantly compared to AES-NI (for 
large requests it is 10 times slower; for small requests it is even worse) 
- see the second table in this document: 
https://people.redhat.com/~mpatocka/benchmarks/qat/kernel-module.txt

QAT has higher priority than AES-NI, so the kernel prefers it (it is not 
used for dm-crypt because it has the flag "CRYPTO_ALG_ALLOCATES_MEMORY", 
but it is preferred over AES-NI in other cases).

AES-NI has priority 300 or 400, unaccelerated AES has 100, so I suggest to 
lower the priority of QAT from 4001 to 201.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>

---
 drivers/crypto/intel/qat/qat_common/qat_algs.c |   12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

Index: linux-2.6/drivers/crypto/intel/qat/qat_common/qat_algs.c
===================================================================
--- linux-2.6.orig/drivers/crypto/intel/qat/qat_common/qat_algs.c
+++ linux-2.6/drivers/crypto/intel/qat/qat_common/qat_algs.c
@@ -1277,7 +1277,7 @@ static struct aead_alg qat_aeads[] = { {
 	.base = {
 		.cra_name = "authenc(hmac(sha1),cbc(aes))",
 		.cra_driver_name = "qat_aes_cbc_hmac_sha1",
-		.cra_priority = 4001,
+		.cra_priority = 201,
 		.cra_flags = CRYPTO_ALG_ASYNC | CRYPTO_ALG_ALLOCATES_MEMORY,
 		.cra_blocksize = AES_BLOCK_SIZE,
 		.cra_ctxsize = sizeof(struct qat_alg_aead_ctx),
@@ -1294,7 +1294,7 @@ static struct aead_alg qat_aeads[] = { {
 	.base = {
 		.cra_name = "authenc(hmac(sha256),cbc(aes))",
 		.cra_driver_name = "qat_aes_cbc_hmac_sha256",
-		.cra_priority = 4001,
+		.cra_priority = 201,
 		.cra_flags = CRYPTO_ALG_ASYNC | CRYPTO_ALG_ALLOCATES_MEMORY,
 		.cra_blocksize = AES_BLOCK_SIZE,
 		.cra_ctxsize = sizeof(struct qat_alg_aead_ctx),
@@ -1311,7 +1311,7 @@ static struct aead_alg qat_aeads[] = { {
 	.base = {
 		.cra_name = "authenc(hmac(sha512),cbc(aes))",
 		.cra_driver_name = "qat_aes_cbc_hmac_sha512",
-		.cra_priority = 4001,
+		.cra_priority = 201,
 		.cra_flags = CRYPTO_ALG_ASYNC | CRYPTO_ALG_ALLOCATES_MEMORY,
 		.cra_blocksize = AES_BLOCK_SIZE,
 		.cra_ctxsize = sizeof(struct qat_alg_aead_ctx),
@@ -1329,7 +1329,7 @@ static struct aead_alg qat_aeads[] = { {
 static struct skcipher_alg qat_skciphers[] = { {
 	.base.cra_name = "cbc(aes)",
 	.base.cra_driver_name = "qat_aes_cbc",
-	.base.cra_priority = 4001,
+	.base.cra_priority = 201,
 	.base.cra_flags = CRYPTO_ALG_ASYNC | CRYPTO_ALG_ALLOCATES_MEMORY,
 	.base.cra_blocksize = AES_BLOCK_SIZE,
 	.base.cra_ctxsize = sizeof(struct qat_alg_skcipher_ctx),
@@ -1347,7 +1347,7 @@ static struct skcipher_alg qat_skciphers
 }, {
 	.base.cra_name = "ctr(aes)",
 	.base.cra_driver_name = "qat_aes_ctr",
-	.base.cra_priority = 4001,
+	.base.cra_priority = 201,
 	.base.cra_flags = CRYPTO_ALG_ASYNC | CRYPTO_ALG_ALLOCATES_MEMORY,
 	.base.cra_blocksize = 1,
 	.base.cra_ctxsize = sizeof(struct qat_alg_skcipher_ctx),
@@ -1365,7 +1365,7 @@ static struct skcipher_alg qat_skciphers
 }, {
 	.base.cra_name = "xts(aes)",
 	.base.cra_driver_name = "qat_aes_xts",
-	.base.cra_priority = 4001,
+	.base.cra_priority = 201,
 	.base.cra_flags = CRYPTO_ALG_ASYNC | CRYPTO_ALG_NEED_FALLBACK |
 			  CRYPTO_ALG_ALLOCATES_MEMORY,
 	.base.cra_blocksize = AES_BLOCK_SIZE,