The object server had a constant KEEP_CACHE_SIZE = 5*1024*1024;
unauthenticated GET requests for files smaller than KEEP_CACHE_SIZE
would not evict the file from the kernel's buffer cache after it was
read from disk.
Now that hardcoded constant is a configuration parameter
("keep_cache_size"), and now there is also another parameter called
"keep_cache_private". If set, then both authenticated and
unauthenticated GET requests for small files will not evict the data
from the buffer cache. The default values are 5 MiB and False,
respectively, so the default behavior is the same.
Bonus: the "mb_per_sync" parameter is now documented in the deployment
guide.
Change-Id: I9a11dbe861f4c23535c6aa82a9111a6fe2db2a59
28cd9b2da8