Page MenuHomeFreeBSD

isci: use maxphys rather than 128KB to size s/g list

Authored by gallatin on Jan 7 2021, 4:26 PM.



In the conversion into a tunable, we converted the
size of the s/g list used by the driver to be based
off of a hardcoded size of 128k rather than maxphys,
this caused performance problems for us. Revert this
to use the maxphys tunable.

Note that this constant is used to size dynamically allocated
things, and not static data structs, and is not constrained
by controller hardware limits, so this is safe.

Diff Detail

R10 FreeBSD src repository
Automatic diff as part of commit; lint not applicable.
Automatic diff as part of commit; unit tests not applicable.

Event Timeline

gallatin created this revision.
This revision is now accepted and ready to land.Jan 7 2021, 4:38 PM

I tested this (at work); it works in our workload (and avoids a severe performance regression).