Re: [PATCH v1 0/8] Batched zswap_store() with compression batching

[Herbert Xu]

On Fri, Oct 16, 2026 at 10:02:13PM -0700, Kanchana P. Sridhar wrote:
>
> > What if you just do the conditional and short-circuit in
> > crypto_acomp_compress?
> 
> Yes, this is the first option I tried (20,946 KB/s).
> 
> [1]:
> 
> int crypto_acomp_compress(struct acomp_req *req)
> {
> struct crypto_acomp *tfm = crypto_acomp_reqtfm(req);
> 
> if (unlikely(acomp_req_on_stack(req) && acomp_is_async(tfm)))
> return -EAGAIN;
> 
> if (likely(req->unit_size && acomp_request_issg(req))) {
> if (likely(!crypto_acomp_req_seg(tfm))) {
> int err = tfm->compress(req);
> 
> req->dst->length = unlikely(err) ? err : req->dlen;
> return err;
> }
> 
> return tfm->compress(req);
> }
> 
> if (crypto_acomp_req_virt(tfm) || acomp_request_issg(req))
> return tfm->compress(req);
> 
> return acomp_do_req_chain(req, true);
> }

That isn't quite right though.  We need to ensure that it really
is a singleton before taking the short-cut.  So you need at
least one conditional:

	if (likely(req->unit_size == req->slen))
		take short-cut

Cheers,
-- 
Email: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt