Messages in this thread | | | Date | Wed, 2 Jun 2010 01:25:11 -0400 (EDT) | From | Mikulas Patocka <> | Subject | Re: [dm-devel] [PATCH] DM-CRYPT: Scale to multiple CPUs |
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On Wed, 2 Jun 2010, Herbert Xu wrote:
> On Wed, Jun 02, 2010 at 01:10:00AM -0400, Mikulas Patocka wrote: > > > > And how can I use pcrypt for dm-crypt? After a quick look at pcrypt > > sources, it seems to be dependent on aead and not useable for general > > encryption algorithms at all. > > You instantiate a pcrypt variant of whatever algorithm that you're > using. For example, if you're using XTS then you should instantiate > pcrypt(xts(aes)). Currently you must use tcrypt to instantiate.
I tried "pcrypt(%s(%s))" in dm-crypt and I get "table: 253:0: crypt: Error allocating crypto tfm"
Are you sure that you know what you're talking about? pcrypt_alloc contains this: switch (algt->type & algt->mask & CRYPTO_ALG_TYPE_MASK) { case CRYPTO_ALG_TYPE_AEAD: return pcrypt_alloc_aead(tb); }
return ERR_PTR(-EINVAL); --- so for anything other byt AEAD it returns -EINVAL.
> > I tried cryptd --- in theory it should work by requesting the algorithm > > like cryptd(cbc(aes)) --- but if I replace "%s(%s)" with "cryptd(%s(%s))" > > in dm-crypt sources it locks up and doesn't work. > > cryptd is something else altogether. However, it certainly should > not lock up. What kernel version is this?
2.6.34 and cryptsetup 1.1.2. It is a soft lockup interruptible with Ctrl-C.
> > > This would be inappropriate for upper layer code as they do not > > > know whether the underlying algorithm should be parallelised, > > > e.g., a PCI offload board certainly should not be parallelised. > > > > The upper layer should ideally request "cbc(aes)" and the crypto routine > > should select the most efficient implementation --- sync on single-core > > system, async with cryptd on multi-core system and async with hardware > > implementation if you have HIFN crypto card. > > That's exactly what will happen when the admin instantiates pcrypt. > dm-crypt simply needs to specify cbc(aes) and it will get pcrypt > automatically. > > The point is that on a modern processor like Nehalem you don't need > pcrypt. > > > It is pointless to track the submitting CPU. > > No you are wrong.
For what? For avoiding cache bounces? But the encrypting is order-of-magnitude slower than memory speed.
Mikulas
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