18259: mention `mksquashfs mem` config setting in singularity.conf

Arvados-DCO-1.1-Signed-off-by: Ward Vandewege <ward@curii.com>

diff --git a/doc/install/singularity.html.textile.liquid b/doc/install/singularity.html.textile.liquid
index bd990b491b77741172d59e773673d99d97fbdc1d..d843912e1ba61b082403b9555458c0c31a23af9c 100644 (file)
--- a/doc/install/singularity.html.textile.liquid
+++ b/doc/install/singularity.html.textile.liquid
@@ -21,6 +21,10 @@ Arvados can be configured to use "Singularity":https://sylabs.io/singularity/ in
 ** The Docker ENTRYPOINT instruction is ignored.
 * Arvados is tested with Singularity version 3.7.4. Other versions may not work.
 
+*Notes*:
+
+* Docker images are converted on the fly by @mksquashfs@, which can consume a considerable amount of RAM. The RAM usage of mksquashfs can be restricted in @/etc/singularity/singularity.conf@ with a line like @mksquashfs mem = 512M@. The amount of memory made available for mksquashfs should be configured lower than the smallest amount of memory requested by a container on the cluster to avoid the conversion being killed for using too much memory.
+
 h2(#configuration). Configuration
 
 To use singularity, first make sure "Singularity is installed":https://sylabs.io/guides/3.7/user-guide/quick_start.html on your cloud worker image or SLURM/LSF compute nodes as applicable. Note @squashfs-tools@ is required.