diff --git a/Documentation/MANPAGE.md b/Documentation/MANPAGE.md index 66956d6..7387424 100644 --- a/Documentation/MANPAGE.md +++ b/Documentation/MANPAGE.md @@ -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