RE: [RFC PATCH v1 01/13] crypto: acomp - Add a poll() operation to acomp_alg and acomp_req

[Sridhar, Kanchana P]

Hi Herbert,

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> From: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
> Sent: Friday, October 18, 2024 12:55 AM
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> Subject: Re: [RFC PATCH v1 01/13] crypto: acomp - Add a poll() operation to
> acomp_alg and acomp_req
> 
> On Thu, Oct 17, 2024 at 11:40:49PM -0700, Kanchana P Sridhar wrote:
> > For async compress/decompress, provide a way for the caller to poll
> > for compress/decompress completion, rather than wait for an interrupt
> > to signal completion.
> >
> > Callers can submit a compress/decompress using crypto_acomp_compress
> > and decompress and rather than wait on a completion, call
> > crypto_acomp_poll() to check for completion.
> >
> > This is useful for hardware accelerators where the overhead of
> > interrupts and waiting for completions is too expensive.  Typically
> > the compress/decompress hw operations complete very quickly and in the
> > vast majority of cases, adding the overhead of interrupt handling and
> > waiting for completions simply adds unnecessary delays and cancels the
> > gains of using the hw acceleration.
> >
> > Signed-off-by: Tom Zanussi <tom.zanussi@xxxxxxxxxxxxxxx>
> > Signed-off-by: Kanchana P Sridhar <kanchana.p.sridhar@xxxxxxxxx>
> > ---
> >  crypto/acompress.c                  |  1 +
> >  include/crypto/acompress.h          | 18 ++++++++++++++++++
> >  include/crypto/internal/acompress.h |  1 +
> >  3 files changed, 20 insertions(+)
> 
> How about just adding a request flag that tells the driver to
> make the request synchronous if possible?
> 
> Something like
> 
> #define CRYPTO_ACOMP_REQ_POLL	0x00000001

Thanks for your code review comments. Are you referring to how the
async/poll interface is enabled at the level of say zswap (by setting a
flag in the acomp_req), followed by the iaa_crypto driver testing for
the flag and submitting the request and returning -EINPROGRESS.
Wouldn't we still need a separate API to do the polling?

I am not the expert on this, and would like to request Kristen's inputs
on whether this is feasible.

Thanks,
Kanchana


> 
> Cheers,
> --
> Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
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