- From: Martin Thomson <martin.thomson@gmail.com>
- Date: Wed, 16 Jan 2013 17:06:19 -0800
- To: James M Snell <jasnell@gmail.com>
- Cc: "ietf-http-wg@w3.org" <ietf-http-wg@w3.org>
James, Any feel for how bohe compares on CPU cost? Ideally, the test harness would provide that information alongside the rest of the data. On 11 January 2013 10:43, James M Snell <jasnell@gmail.com> wrote: > Just continuing my investigation of various header compression strategies > around the BOHE mechanism. In my personal github fork, I have just checked > in two bohe variations, one that implements selective-compression, the other > implements isolated-compression.. > > https://github.com/jasnell/compression-test/tree/master/compressor/bohe2 > https://github.com/jasnell/compression-test/tree/master/compressor/bohe3 > > With bohe2 (selective-compression), a header block can consist of a > compressed set of headers and an uncompressed set of headers. Specific > headers such as Cookie, Set-Cookie, etc can be marked as "Do Not Compress". > These are dropped into the frame as-is and thus avoid the CRIME issue > completely. The rest of the headers are compressed using gzip using the > existing spdy3 dictionary. Obviously this is not ideal because Cookie data > then is passed around without any compression at all, making it far less > efficient than any of the other options on the table. > > In bohe3 (isolated-compression), a header block can consist of two separate > compressed blocks generated using two separate stream compressor instances. > Selected headers (like Cookie) can be included in the secondary isolated > block which would never contain general user-provided header data. > > **These are only experiments right now and are not intended as serious > proposals for the spec**. Isolated-compression (bohe3) does show promise > however. If we can successfully isolate potentially sensitive headers into > their own compression context generated independently of any general > user-supplied data, we can effectively short-circuit the CRIME attack by > making it impossible for an attacker to compare values based on the > compression ratio... and since it still uses gzip compression, we achieve a > generally better compression ratio overall than we get with the proposed > delta encoding. For now, tho, just consider this all just to be fodder for > discussion. There are still MANY issues with these experimental approaches > and I still need to go through delta in more detail to see if there is a way > bohe and delta can be used effectively together. > > Just for example... > > james-snells-macbook-pro:compression-test james$ ./compare_compressors.py -c > bohe3 -c bohe2 -c bohe -c delta -t > /Users/james/git/http_samples/mnot/amazon.com.har > 732 req messages processed > compressed | ratio min max std > req bohe 26,035 | 0.13 0.03 0.68 0.08 > req bohe2 44,195 | 0.23 0.07 0.71 0.13 > req bohe3 30,944 | 0.16 0.05 0.74 0.08 > req delta 33,955 | 0.17 0.02 0.71 0.09 > req http1 195,386 | 1.00 1.00 1.00 0.00 > > 732 res messages processed > compressed | ratio min max std > res bohe 39,525 | 0.25 0.04 0.67 0.07 > res bohe2 47,157 | 0.29 0.12 0.71 0.08 > res bohe3 44,843 | 0.28 0.06 0.70 0.07 > res delta 44,499 | 0.28 0.02 0.65 0.09 > res http1 159,968 | 1.00 1.00 1.00 0.00 > > - James > > > > On Thu, Jan 10, 2013 at 11:08 AM, James M Snell <jasnell@gmail.com> wrote: >> >> I have an initial bohe implementation for the compression tests... it's >> very preliminary and uses the same gzip compression as the current spdy3. >> I'm going to be playing around with the delta compression mechanism as well >> and see how much of an impact that has. Initial results are very promising >> but I haven't done much debugging yet. Just wanted folks to know that this >> work was underway... >> >> https://github.com/jasnell/compression-test/tree/master/compressor/bohe >> >> Some test runs.... >> >> ./compare_compressors.py -c bohe -c spdy3 -c delta >> ../http_samples/mnot/amazon.com.har >> 732 req messages processed >> compressed | ratio min max std >> req bohe 26,122 | 0.13 0.04 0.70 0.08 >> req delta 33,955 | 0.17 0.02 0.71 0.09 >> req http1 195,386 | 1.00 1.00 1.00 0.00 >> req spdy3 27,238 | 0.14 0.04 0.71 0.08 >> >> 732 res messages processed >> compressed | ratio min max std >> res bohe 39,628 | 0.25 0.04 0.66 0.07 >> res delta 44,499 | 0.28 0.02 0.65 0.09 >> res http1 159,968 | 1.00 1.00 1.00 0.00 >> res spdy3 41,325 | 0.26 0.04 0.67 0.08 >> >> >> ./compare_compressors.py -c bohe -c spdy3 -c delta >> ../http_samples/mnot/craigslist.org.har >> 66 req messages processed >> compressed | ratio min max std >> req bohe 1,948 | 0.15 0.06 0.73 0.11 >> req delta 2,036 | 0.16 0.07 0.71 0.11 >> req http1 12,894 | 1.00 1.00 1.00 0.00 >> req spdy3 2,016 | 0.16 0.07 0.75 0.11 >> >> 66 res messages processed >> compressed | ratio min max std >> res bohe 1,786 | 0.18 0.07 0.77 0.13 >> res delta 2,858 | 0.28 0.08 0.69 0.12 >> res http1 10,147 | 1.00 1.00 1.00 0.00 >> res spdy3 1,869 | 0.18 0.09 0.78 0.13 >> >> >> ./compare_compressors.py -c bohe -c spdy3 -c delta >> ../http_samples/mnot/flickr.com.har >> 438 req messages processed >> compressed | ratio min max std >> req bohe 11,988 | 0.10 0.02 0.69 0.07 >> req delta 26,372 | 0.22 0.01 0.71 0.14 >> req http1 121,854 | 1.00 1.00 1.00 0.00 >> req spdy3 12,550 | 0.10 0.02 0.71 0.07 >> >> 438 res messages processed >> compressed | ratio min max std >> res bohe 13,073 | 0.09 0.05 0.66 0.06 >> res delta 25,236 | 0.18 0.02 0.70 0.11 >> res http1 140,457 | 1.00 1.00 1.00 0.00 >> res spdy3 14,142 | 0.10 0.05 0.66 0.06 >> >> >> ./compare_compressors.py -c bohe -c spdy3 -c delta >> ../http_samples/mnot/facebook.com.har >> 234 req messages processed >> compressed | ratio min max std >> req bohe 6,091 | 0.15 0.06 0.78 0.07 >> req delta 7,800 | 0.19 0.02 0.70 0.07 >> req http1 41,980 | 1.00 1.00 1.00 0.00 >> req spdy3 6,301 | 0.15 0.06 0.77 0.07 >> >> 234 res messages processed >> compressed | ratio min max std >> res bohe 9,458 | 0.23 0.07 0.68 0.07 >> res delta 12,045 | 0.30 0.13 0.60 0.08 >> res http1 40,252 | 1.00 1.00 1.00 0.00 >> res spdy3 9,788 | 0.24 0.07 0.69 0.07 >> >> >> >> >
Received on Thursday, 17 January 2013 01:06:47 UTC