On 5/31/23 10:08, Richard Henderson wrote:
On 5/31/23 09:47, Ard Biesheuvel wrote:
On Wed, 31 May 2023 at 18:33, Richard Henderson
Thanks. I spent some time yesterday looking at this, with an encrypted disk
test case and
could only measure 0.6% and 0.5% for total overhead of decrypt and encrypt
respectively.
I don't understand what 'overhead' means in this context. Are you
saying you saw barely any improvement?
I saw, without changes, just over 1% of total system emulation time was devoted to aes,
which gives an upper limit to the runtime improvement possible there. But I'll have a
look at tcrypt.
Using
# insmod /lib/modules/5.10.0-21-arm64/kernel/crypto/tcrypt.ko mode=600 sec=10
I see
25.50% qemu-system-aar qemu-system-aarch64 [.] helper_crypto_aese
25.36% qemu-system-aar qemu-system-aarch64 [.] helper_crypto_aesmc
6.66% qemu-system-aar qemu-system-aarch64 [.] rebuild_hflags_a64
3.25% qemu-system-aar qemu-system-aarch64 [.] tb_lookup
2.52% qemu-system-aar qemu-system-aarch64 [.] fp_exception_el
2.35% qemu-system-aar qemu-system-aarch64 [.] helper_lookup_tb_ptr
Obviously a crypto-heavy test, but 51% of runtime is certainly worth more work.
r~
