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From:   Olga Kornievskaia <aglo@umich.edu>
Date:   Tue, 26 Jul 2022 15:45:36 -0400
Message-ID: <CAN-5tyEgRvvFq51kdT-ROo-ew71JE610Da=Cqf_Ya4dgYxEmKg@mail.gmail.com>
Subject: Re: [PATCH v1 00/11] Put struct nfsd4_copy on a diet
To:     Chuck Lever <chuck.lever@oracle.com>
Cc:     linux-nfs <linux-nfs@vger.kernel.org>
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Chuck,

Are there pre-reqs for this series? I had tried to apply the patches
on top of 5-19-rc6 but I get the following compile error:

fs/nfsd/nfs4proc.c: In function =E2=80=98nfsd4_setup_inter_ssc=E2=80=99:
fs/nfsd/nfs4proc.c:1539:34: error: passing argument 1 of
=E2=80=98nfsd4_interssc_connect=E2=80=99 from incompatible pointer type
[-Werror=3Dincompatible-pointer-types]
  status =3D nfsd4_interssc_connect(&copy->cp_src, rqstp, mount);
                                  ^~~~~~~~~~~~~
fs/nfsd/nfs4proc.c:1414:43: note: expected =E2=80=98struct nl4_server *=E2=
=80=99 but
argument is of type =E2=80=98struct nl4_server **=E2=80=99
 nfsd4_interssc_connect(struct nl4_server *nss, struct svc_rqst *rqstp,
                        ~~~~~~~~~~~~~~~~~~~^~~
cc1: some warnings being treated as errors
make[2]: *** [scripts/Makefile.build:249: fs/nfsd/nfs4proc.o] Error 1
make[1]: *** [scripts/Makefile.build:466: fs/nfsd] Error 2
make: *** [Makefile:1843: fs] Error 2

On Fri, Jul 22, 2022 at 4:36 PM Chuck Lever <chuck.lever@oracle.com> wrote:
>
> While testing NFSD for-next, I noticed svc_generic_init_request()
> was an unexpected hot spot on NFSv4 workloads. Drilling into the
> perf report, it shows that the hot path in there is:
>
> 1208         memset(rqstp->rq_argp, 0, procp->pc_argsize);
> 1209         memset(rqstp->rq_resp, 0, procp->pc_ressize);
>
> For an NFSv4 COMPOUND,
>
>         procp->pc_argsize =3D sizeof(nfsd4_compoundargs),
>
> struct nfsd4_compoundargs on my system is more than 17KB! This is
> due to the size of the iops field:
>
>         struct nfsd4_op                 iops[8];
>
> Each struct nfsd4_op contains a union of the arguments for each
> NFSv4 operation. Each argument is typically less than 128 bytes
> except that struct nfsd4_copy and struct nfsd4_copy_notify are both
> larger than 2KB each.
>
> I'm not yet totally convinced this series never orphans memory, but
> it does reduce the size of nfsd4_compoundargs to just over 4KB. This
> is still due to struct nfsd4_copy being almost 500 bytes. I don't
> see more low-hanging fruit there, though.
>
> ---
>
> Chuck Lever (11):
>       NFSD: Shrink size of struct nfsd4_copy_notify
>       NFSD: Shrink size of struct nfsd4_copy
>       NFSD: Reorder the fields in struct nfsd4_op
>       NFSD: Make nfs4_put_copy() static
>       NFSD: Make boolean fields in struct nfsd4_copy into atomic bit flag=
s
>       NFSD: Refactor nfsd4_cleanup_inter_ssc() (1/2)
>       NFSD: Refactor nfsd4_cleanup_inter_ssc() (2/2)
>       NFSD: Refactor nfsd4_do_copy()
>       NFSD: Remove kmalloc from nfsd4_do_async_copy()
>       NFSD: Add nfsd4_send_cb_offload()
>       NFSD: Move copy offload callback arguments into a separate structur=
e
>
>
>  fs/nfsd/nfs4callback.c |  37 +++++----
>  fs/nfsd/nfs4proc.c     | 165 +++++++++++++++++++++--------------------
>  fs/nfsd/nfs4xdr.c      |  30 +++++---
>  fs/nfsd/state.h        |   1 -
>  fs/nfsd/xdr4.h         |  54 ++++++++++----
>  5 files changed, 163 insertions(+), 124 deletions(-)
>
> --
> Chuck Lever
>