Disable prefetch in AES for now. Problem: with iterative modes like CBC,

the prefetch is called for each block of input, and so a total of
(4096+256)/64 = 68 prefetches are executed for each block. This reduces
performance of iterative modes dramatically.

I'm not sure what the right approach for dealing with this is.

2 files changed, 0 insertions, 20 deletions

diff --git a/src/block/aes/aes.cpp b/src/block/aes/aes.cpp
index 8ef9cd8fe..34698ae7f 100644
--- a/src/block/aes/aes.cpp
+++ b/src/block/aes/aes.cpp
@@ -20,10 +20,6 @@ void AES::encrypt_n(const byte in[], byte out[], u32bit blocks) const
    const u32bit* TE2 = TE + 512;
    const u32bit* TE3 = TE + 768;
 
-   PREFETCH::readonly(TE, 1024);
-   PREFETCH::readonly(SE, 256);
-   PREFETCH::cipher_fetch(in, out, blocks, this->BLOCK_SIZE);
-
    for(u32bit i = 0; i != blocks; ++i)
       {
       u32bit T0 = load_be<u32bit>(in, 0) ^ EK[0];
@@ -118,10 +114,6 @@ void AES::decrypt_n(const byte in[], byte out[], u32bit blocks) const
    const u32bit* TD2 = TD + 512;
    const u32bit* TD3 = TD + 768;
 
-   PREFETCH::readonly(TD, 1024);
-   PREFETCH::readonly(SD, 256);
-   PREFETCH::cipher_fetch(in, out, blocks, this->BLOCK_SIZE);
-
    for(u32bit i = 0; i != blocks; ++i)
       {
       u32bit T0 = load_be<u32bit>(in, 0) ^ DK[0];
diff --git a/src/utils/prefetch.h b/src/utils/prefetch.h
index 72b6de689..7afdbda0a 100644
--- a/src/utils/prefetch.h
+++ b/src/utils/prefetch.h
@@ -36,18 +36,6 @@ inline void readwrite(const T* addr, u32bit length)
 #endif
    }
 
-inline void cipher_fetch(const byte* in_block,
-                         const byte* out_block,
-                         u32bit blocks,
-                         u32bit block_size)
-   {
-   // Only prefetch input specifically if in != out
-   if(in_block != out_block)
-      readonly(in_block, blocks * block_size);
-
-   readwrite(out_block, blocks * block_size);
-   }
-
 }
 
 }