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server: rest: switch from fastest to default deflate compression level

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I made some comparision with bombardier[0], the one listed here are
30s looped requests with two concurrent clients:

[ static download of ext-all.js ]:
  lvl                              avg /   stdev  / max
 none        1.98 MiB  100 %    5.17ms /  1.30ms / 32.38ms
 fastest   813.14 KiB   42 %   20.53ms /  2.85ms / 58.71ms
 default   626.35 KiB   30 %   39.70ms /  3.98ms / 85.47ms

[ deterministic (pre-defined data), but real API call ]:
  lvl                              avg /   stdev  / max
 none      129.09 KiB  100 %    2.70ms / 471.58us / 26.93ms
 fastest    42.12 KiB   33 %    3.47ms / 606.46us / 32.42ms
 default    34.82 KiB   27 %    4.28ms / 737.99us / 33.75ms

The reduction is quite better with default, but it's also slower, but
only when testing over unconstrained network. For real world
scenarios where compression actually matters, e.g., when using a
spotty train connection, we will be faster again with better
compression.

A GPRS limited connection (Firefox developer console) requires the
following load (until the DOMContentLoaded event triggered) times:
  lvl        t      x faster
 none      9m 18.6s   x 1.0
 fastest   3m 20.0s   x 2.8
 default   2m 30.0s   x 3.7

So for worst case using sligthly more CPU time on the server has a
tremendous effect on the client load time.

Using a more realistical example and limiting for "Good 2G" gives:

 none      1m  1.8s   x 1.0
 fastest      22.6s   x 2.7
 default      16.6s   x 3.7

16s is somewhat OK, >1m just isn't...

So, use default level to ensure we get bearable load times on
clients, and if we want to improve transmission size AND speed then
we could always use a in-memory cache, only a few MiB would be
required for the compressable static files we server.

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>
This commit is contained in:
Thomas Lamprecht 2021-04-07 17:12:01 +02:00
parent d84e4073af
commit b84e8aaee9
1 changed files with 3 additions and 3 deletions
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6
src/server/rest.rs
View File

@ -443,7 +443,7 @@ pub async fn handle_api_request<Env: RpcEnvironment, S: 'static + BuildHasher +
body.map_err(|err| {
proxmox::io_format_err!("error during compression: {}", err)
}),
Level::Fastest,
Level::Default,
))
})
}
@ -561,7 +561,7 @@ async fn simple_static_file_download(
let mut response = match compression {
Some(CompressionMethod::Deflate) => {
let mut enc = DeflateEncoder::with_quality(data, Level::Fastest);
let mut enc = DeflateEncoder::with_quality(data, Level::Default);
enc.compress_vec(&mut file, CHUNK_SIZE_LIMIT as usize).await?;
let mut response = Response::new(enc.into_inner().into());
response.headers_mut().insert(
@ -607,7 +607,7 @@ async fn chuncked_static_file_download(
);
Body::wrap_stream(DeflateEncoder::with_quality(
AsyncReaderStream::new(file),
Level::Fastest,
Level::Default,
))
}
None => Body::wrap_stream(AsyncReaderStream::new(file)),