Cassandra QAT update optimization

[ssherman8]

The purpose of this PR is show benefits of using Cassandra with QAT. It has been reviewed by both the Java team and the QAT team. The PCR for the performance claim was approved in PCR-1423

[rsiyer-intel]

Provide link to zlib-accel repo here (than in references) and
probably add explicit clone to /opt/zlib-accel, since you have that path in the next LD_PRELOAD command.

[harp-intel]

Claude Code review:

Summary

This PR adds a new guide (software/cassandra/QAT/README.md) for using Cassandra with Intel QAT hardware-accelerated compression via the zlib-accel
library. It also adds a link in the root README.md. +168 lines, 2 files changed.

Existing Review Comments (by rsiyer-intel)

There are 4 unresolved comments that should be addressed:

1. L89 — Typo: "package manger" → "package manager"
2. L148 — "6 independent Cassandra servers and servers" — likely should be "clients and servers"
3. L120 — Missing link to the zlib-accel repo in the build section + should add an explicit git clone to /opt/zlib-accel since that path is referenced in
   the LD_PRELOAD command
4. L163 — Typo in references: "zib-accel" → "zlib-accel"

Additional Issues I Found

Typos / grammar:

• L30: "be reading to use" → "be ready to use"
• L48: "The output of the command with be" → "will be"
• L89: "that with the distribution's" → "them with the distribution's"
• L108: broken markdown link [optimization-zone] (https://...) — remove the space before (
• L153: broken markdown link [enhancement proposal] (https://...) — same space issue
• L40: duplicate wget commands — qat_4xxx.bin is downloaded twice instead of qat_4xxx_mmp.bin, and same pattern for qat_402xx and qat_420xx (the _mmp.bin
  variants are missing)

Content issues:

• L12: ToC anchor #Details has capital D but the heading is ## Details — may not link correctly depending on renderer (GitHub lowercases anchors, so
  #details would be correct)
• L119: The cmake command has -CMAKE_BUILD_TYPE=Release — should this be -DCMAKE_BUILD_TYPE=Release?
• L148: No mention of the NoSQLBench workload parameters (e.g., thread count, duration) — would help reproducibility
• The firmware download section downloads both .bin and _mmp.bin variants but the wget commands only fetch .bin files (duplicated) — the _mmp.bin files
  are never actually downloaded

Missing context:

• No link or instructions for where to get the zlib-accel source code before the build steps (aligns with rsiyer-intel's comment)
• The cassandra.yaml compression settings aren't shown — readers need to know which sstable_compression class to use with zlib

Overall the guide covers the right topics but needs a pass for typos, broken links, and the duplicate/missing firmware download commands before merging.

[rsiyer-intel]

Do you have any performance charts that can be shared besides the summary in the Overview section?
And any commandlines used for NoSQLBench if anyone wants to reproduce the results.

[rsiyer-intel]

Thanks Sri. Left few comments and suggestions.

[rsiyer-intel]

zlib-accel can be built with.
Remove space after [zlib-accel]

[rsiyer-intel]

Why do we need zlib-accel build steps twice?
Is it once for generic build and once for Cassandra?
It's not clear, does the /etc/zlib-accel.conf change when building for Cassandra?
If everything is same, then probably we don't need build steps twice. Leave it up to you.