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Cc:     Anna.Schumaker@Netapp.com
Subject: [PATCH v5 0/5] NFSD: Add support for the v4.2 READ_PLUS operation
Date:   Tue,  8 Sep 2020 12:25:54 -0400
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From: Anna Schumaker <Anna.Schumaker@Netapp.com>

These patches add server support for the READ_PLUS operation, which
breaks read requests into several "data" and "hole" segments when
replying to the client.

- Changes since v4:
  - Fix up nfsd4_read_plus_rsize() calculation
  - Return a short read if we detect the file has changed during
    encoding
  - Rebase to v5.9-rc4

Here are the results of some performance tests I ran on some lab
machines. I tested by reading various 2G files from a few different underlying
filesystems and across several NFS versions. I used the `vmtouch` utility
to make sure files were only cached when we wanted them to be. In addition
to 100% data and 100% hole cases, I also tested with files that alternate
between data and hole segments. These files have either 4K, 8K, 16K, or 32K
segment sizes and start with either data or hole segments. So the file
mixed-4d has a 4K segment size beginning with a data segment, but mixed-32h
has 32K segments beginning with a hole. The units are in seconds, with the
first number for each NFS version being the uncached read time and the second
number is for when the file is cached on the server.

I added some extra data collection (client cpu percentage and sys time),
but the extra data means I couldn't figure out a way to break this down
into a concise table. I cut out v3 and v4.0 performance numbers to get
the size down, but I kept v4.1 for comparison because it uses the same
code that v4.2 without read plus uses.


Read Plus Results (ext4):
  data
   :... v4.1 ... Uncached ... 20.540 s, 105 MB/s, 0.65 s kern, 3% cpu
   :    :....... Cached ..... 18.252 s, 118 MB/s, 0.70 s kern, 3% cpu
   :... v4.2 ... Uncached ... 20.605 s, 104 MB/s, 0.65 s kern, 3% cpu
        :....... Cached ..... 18.253 s, 118 MB/s, 0.67 s kern, 3% cpu
  hole
   :... v4.1 ... Uncached ... 18.255 s, 118 MB/s, 0.72 s kern,  3% cpu
   :    :....... Cached ..... 18.252 s, 118 MB/s, 0.72 s kern,  3% cpu
   :... v4.2 ... Uncached ...  0.847 s, 2.5 GB/s, 0.73 s kern, 86% cpu
        :....... Cached .....  0.845 s, 2.5 GB/s, 0.72 s kern, 85% cpu
  mixed-4d
   :... v4.1 ... Uncached ... 54.691 s,  39 MB/s, 0.75 s kern, 1% cpu
   :    :....... Cached ..... 18.252 s, 118 MB/s, 0.71 s kern, 3% cpu
   :... v4.2 ... Uncached ... 51.587 s,  42 MB/s, 0.75 s kern, 1% cpu
        :....... Cached .....  9.215 s, 233 MB/s, 0.67 s kern, 7% cpu
  mixed-8d
   :... v4.1 ... Uncached ... 37.072 s,  58 MB/s, 0.67 s kern, 1% cpu
   :    :....... Cached ..... 18.252 s, 118 MB/s, 0.71 s kern, 3% cpu
   :... v4.2 ... Uncached ... 33.259 s,  65 MB/s, 0.68 s kern, 2% cpu
        :....... Cached .....  9.172 s, 234 MB/s, 0.67 s kern, 7% cpu
  mixed-16d
   :... v4.1 ... Uncached ... 27.138 s,  79 MB/s, 0.73 s kern, 2% cpu
   :    :....... Cached ..... 18.252 s, 118 MB/s, 0.71 s kern, 3% cpu
   :... v4.2 ... Uncached ... 23.042 s,  93 MB/s, 0.73 s kern, 3% cpu
        :....... Cached .....  9.150 s, 235 MB/s, 0.66 s kern, 7% cpu
  mixed-32d
   :... v4.1 ... Uncached ... 25.326 s,  85 MB/s, 0.68 s kern, 2% cpu
   :    :....... Cached ..... 18.252 s, 118 MB/s, 0.70 s kern, 3% cpu
   :... v4.2 ... Uncached ... 21.125 s, 102 MB/s, 0.69 s kern, 3% cpu
        :....... Cached .....  9.140 s, 235 MB/s, 0.67 s kern, 7% cpu
  mixed-4h
   :... v4.1 ... Uncached ... 58.317 s,  37 MB/s, 0.75 s kern, 1% cpu
   :    :....... Cached ..... 18.252 s, 118 MB/s, 0.70 s kern, 3% cpu
   :... v4.2 ... Uncached ... 51.878 s,  41 MB/s, 0.74 s kern, 1% cpu
        :....... Cached .....  9.215 s, 233 MB/s, 0.68 s kern, 7% cpu
  mixed-8h
   :... v4.1 ... Uncached ... 36.855 s,  58 MB/s, 0.68 s kern, 1% cpu
   :    :....... Cached ..... 18.252 s, 118 MB/s, 0.72 s kern, 3% cpu
   :... v4.2 ... Uncached ... 29.457 s,  73 MB/s, 0.68 s kern, 2% cpu
        :....... Cached .....  9.172 s, 234 MB/s, 0.67 s kern, 7% cpu
  mixed-16h
   :... v4.1 ... Uncached ... 26.460 s,  81 MB/s, 0.74 s kern, 2% cpu
   :    :....... Cached ..... 18.252 s, 118 MB/s, 0.71 s kern, 3% cpu
   :... v4.2 ... Uncached ... 19.587 s, 110 MB/s, 0.74 s kern, 3% cpu
        :....... Cached .....  9.150 s, 235 MB/s, 0.67 s kern, 7% cpu
  mixed-32h
   :... v4.1 ... Uncached ... 25.495 s,  84 MB/s, 0.69 s kern, 2% cpu
   :    :....... Cached ..... 18.252 s, 118 MB/s, 0.65 s kern, 3% cpu
   :... v4.2 ... Uncached ... 17.634 s, 122 MB/s, 0.69 s kern, 3% cpu
        :....... Cached .....  9.140 s, 235 MB/s, 0.68 s kern, 7% cpu


Read Plus Results (xfs):
  data
   :... v4.1 ... Uncached ... 20.230 s, 106 MB/s, 0.65 s kern, 3% cpu
   :    :....... Cached ..... 18.252 s, 118 MB/s, 0.68 s kern, 3% cpu
   :... v4.2 ... Uncached ... 20.724 s, 104 MB/s, 0.65 s kern, 3% cpu
        :....... Cached ..... 18.253 s, 118 MB/s, 0.67 s kern, 3% cpu
  hole
   :... v4.1 ... Uncached ... 18.255 s, 118 MB/s, 0.68 s kern,  3% cpu
   :    :....... Cached ..... 18.252 s, 118 MB/s, 0.69 s kern,  3% cpu
   :... v4.2 ... Uncached ...  0.904 s, 2.4 GB/s, 0.72 s kern, 79% cpu
        :....... Cached .....  0.908 s, 2.4 GB/s, 0.73 s kern, 80% cpu
  mixed-4d
   :... v4.1 ... Uncached ... 57.553 s,  37 MB/s, 0.77 s kern, 1% cpu
   :    :....... Cached ..... 18.252 s, 118 MB/s, 0.70 s kern, 3% cpu
   :... v4.2 ... Uncached ... 37.162 s,  58 MB/s, 0.73 s kern, 1% cpu
        :....... Cached .....  9.215 s, 233 MB/s, 0.67 s kern, 7% cpu
  mixed-8d
   :... v4.1 ... Uncached ... 36.754 s,  58 MB/s, 0.69 s kern, 1% cpu
   :    :....... Cached ..... 18.252 s, 118 MB/s, 0.68 s kern, 3% cpu
   :... v4.2 ... Uncached ... 24.454 s,  88 MB/s, 0.69 s kern, 2% cpu
        :....... Cached .....  9.172 s, 234 MB/s, 0.66 s kern, 7% cpu
  mixed-16d
   :... v4.1 ... Uncached ... 27.156 s,  79 MB/s, 0.73 s kern, 2% cpu
   :    :....... Cached ..... 18.252 s, 118 MB/s, 0.71 s kern, 3% cpu
   :... v4.2 ... Uncached ... 22.934 s,  94 MB/s, 0.72 s kern, 3% cpu
        :....... Cached .....  9.150 s, 235 MB/s, 0.68 s kern, 7% cpu
  mixed-32d
   :... v4.1 ... Uncached ... 27.849 s,  77 MB/s, 0.68 s kern, 2% cpu
   :    :....... Cached ..... 18.252 s, 118 MB/s, 0.72 s kern, 3% cpu
   :... v4.2 ... Uncached ... 23.670 s,  91 MB/s, 0.67 s kern, 2% cpu
        :....... Cached .....  9.139 s, 235 MB/s, 0.64 s kern, 7% cpu
  mixed-4h
   :... v4.1 ... Uncached ... 57.639 s,  37 MB/s, 0.72 s kern, 1% cpu
   :    :....... Cached ..... 18.252 s, 118 MB/s, 0.69 s kern, 3% cpu
   :... v4.2 ... Uncached ... 35.503 s,  61 MB/s, 0.72 s kern, 2% cpu
        :....... Cached .....  9.215 s, 233 MB/s, 0.66 s kern, 7% cpu
  mixed-8h
   :... v4.1 ... Uncached ... 37.044 s,  58 MB/s, 0.71 s kern, 1% cpu
   :    :....... Cached ..... 18.252 s, 118 MB/s, 0.68 s kern, 3% cpu
   :... v4.2 ... Uncached ... 23.779 s,  90 MB/s, 0.69 s kern, 2% cpu
        :....... Cached .....  9.172 s, 234 MB/s, 0.65 s kern, 7% cpu
  mixed-16h
   :... v4.1 ... Uncached ... 27.167 s,  79 MB/s, 0.73 s kern, 2% cpu
   :    :....... Cached ..... 18.252 s, 118 MB/s, 0.67 s kern, 3% cpu
   :... v4.2 ... Uncached ... 19.088 s, 113 MB/s, 0.75 s kern, 3% cpu
        :....... Cached .....  9.159 s, 234 MB/s, 0.66 s kern, 7% cpu
  mixed-32h
   :... v4.1 ... Uncached ... 27.592 s,  78 MB/s, 0.71 s kern, 2% cpu
   :    :....... Cached ..... 18.252 s, 118 MB/s, 0.68 s kern, 3% cpu
   :... v4.2 ... Uncached ... 19.682 s, 109 MB/s, 0.67 s kern, 3% cpu
        :....... Cached .....  9.140 s, 235 MB/s, 0.67 s kern, 7% cpu


Read Plus Results (btrfs):
  data
   :... v4.1 ... Uncached ... 21.317 s, 101 MB/s, 0.63 s kern, 2% cpu
   :    :....... Cached ..... 18.252 s, 118 MB/s, 0.67 s kern, 3% cpu
   :... v4.2 ... Uncached ... 28.665 s,  75 MB/s, 0.65 s kern, 2% cpu
        :....... Cached ..... 18.253 s, 118 MB/s, 0.66 s kern, 3% cpu
  hole
   :... v4.1 ... Uncached ... 18.256 s, 118 MB/s, 0.70 s kern,  3% cpu
   :    :....... Cached ..... 18.254 s, 118 MB/s, 0.73 s kern,  4% cpu
   :... v4.2 ... Uncached ...  0.851 s, 2.5 GB/s, 0.72 s kern, 84% cpu
        :....... Cached .....  0.847 s, 2.5 GB/s, 0.73 s kern, 86% cpu
  mixed-4d
   :... v4.1 ... Uncached ... 56.857 s,  38 MB/s, 0.76 s kern, 1% cpu
   :    :....... Cached ..... 18.252 s, 118 MB/s, 0.72 s kern, 3% cpu
   :... v4.2 ... Uncached ... 54.455 s,  39 MB/s, 0.73 s kern, 1% cpu
        :....... Cached .....  9.215 s, 233 MB/s, 0.68 s kern, 7% cpu
  mixed-8d
   :... v4.1 ... Uncached ... 36.641 s,  59 MB/s, 0.68 s kern, 1% cpu
   :    :....... Cached ..... 18.252 s, 118 MB/s, 0.70 s kern, 3% cpu
   :... v4.2 ... Uncached ... 33.205 s,  65 MB/s, 0.67 s kern, 2% cpu
        :....... Cached .....  9.172 s, 234 MB/s, 0.65 s kern, 7% cpu
  mixed-16d
   :... v4.1 ... Uncached ... 28.653 s,  75 MB/s, 0.72 s kern, 2% cpu
   :    :....... Cached ..... 18.252 s, 118 MB/s, 0.70 s kern, 3% cpu
   :... v4.2 ... Uncached ... 25.748 s,  83 MB/s, 0.71 s kern, 2% cpu
        :....... Cached .....  9.150 s, 235 MB/s, 0.64 s kern, 7% cpu
  mixed-32d
   :... v4.1 ... Uncached ... 28.886 s,  74 MB/s, 0.67 s kern, 2% cpu
   :    :....... Cached ..... 18.252 s, 118 MB/s, 0.71 s kern, 3% cpu
   :... v4.2 ... Uncached ... 24.724 s,  87 MB/s, 0.74 s kern, 2% cpu
        :....... Cached .....  9.140 s, 235 MB/s, 0.63 s kern, 6% cpu
  mixed-4h
   :... v4.1 ... Uncached ...  52.181 s,  41 MB/s, 0.73 s kern, 1% cpu
   :    :....... Cached .....  18.252 s, 118 MB/s, 0.66 s kern, 3% cpu
   :... v4.2 ... Uncached ... 150.341 s,  14 MB/s, 0.72 s kern, 0% cpu
        :....... Cached .....   9.216 s, 233 MB/s, 0.63 s kern, 6% cpu
  mixed-8h
   :... v4.1 ... Uncached ... 36.945 s,  58 MB/s, 0.68 s kern, 1% cpu
   :    :....... Cached ..... 18.252 s, 118 MB/s, 0.65 s kern, 3% cpu
   :... v4.2 ... Uncached ... 79.781 s,  27 MB/s, 0.68 s kern, 0% cpu
        :....... Cached .....  9.172 s, 234 MB/s, 0.66 s kern, 7% cpu
  mixed-16h
   :... v4.1 ... Uncached ... 28.651 s,  75 MB/s, 0.73 s kern, 2% cpu
   :    :....... Cached ..... 18.252 s, 118 MB/s, 0.66 s kern, 3% cpu
   :... v4.2 ... Uncached ... 47.428 s,  45 MB/s, 0.71 s kern, 1% cpu
        :....... Cached .....  9.150 s, 235 MB/s, 0.67 s kern, 7% cpu
  mixed-32h
   :... v4.1 ... Uncached ... 28.618 s,  75 MB/s, 0.69 s kern, 2% cpu
   :    :....... Cached ..... 18.252 s, 118 MB/s, 0.70 s kern, 3% cpu
   :... v4.2 ... Uncached ... 38.813 s,  55 MB/s, 0.67 s kern, 1% cpu
        :....... Cached .....  9.140 s, 235 MB/s, 0.61 s kern, 6% cpu


Thoughts?
Anna


Anna Schumaker (5):
  SUNRPC/NFSD: Implement xdr_reserve_space_vec()
  NFSD: Add READ_PLUS data support
  NFSD: Add READ_PLUS hole segment encoding
  NFSD: Return both a hole and a data segment
  NFSD: Encode a full READ_PLUS reply

 fs/nfsd/nfs4proc.c         |  20 +++++
 fs/nfsd/nfs4xdr.c          | 173 +++++++++++++++++++++++++++++++------
 include/linux/sunrpc/xdr.h |   2 +
 net/sunrpc/xdr.c           |  45 ++++++++++
 4 files changed, 213 insertions(+), 27 deletions(-)

-- 
2.28.0