MANPAGE: document "-serialize_reads"

This commit is contained in:
Jakob Unterwurzacher 2017-03-19 20:23:49 +01:00
parent d2e9e8e2f8
commit b78c3bd516
1 changed files with 18 additions and 0 deletions

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@ -181,6 +181,24 @@ Options:
**-ro**
: Mount the filesystem read-only
**-serialize_reads**
: The kernel usually submits multiple concurrent reads to service
userspace requests and kernel readahead. gocryptfs serves them
concurrently and in arbitrary order. On backing storage that performs
poorly for concurrent or out-of-order reads (like Amazon Cloud Drive),
this behavoir can cause very slow read speeds.
The `-serialize_reads`
option does two things: (1) reads will be submitted one-by-one (no
concurrency) and (2) gocryptfs tries to order the reads by file
offset order.
The ordering requires gocryptfs to wait a certain time before
submitting a read. The serialization introduces extra locking.
These factors will limit throughput to below 70MB/s.
For more details visit https://github.com/rfjakob/gocryptfs/issues/92 .
**-scryptn int**
: scrypt cost parameter logN. Setting this to a lower value speeds up
mounting but makes the password susceptible to brute-force attacks