Bug 235543
| Summary: | 19.6.1. Tuning: Inaccurate description of vfs.zfs.arc_max | ||
|---|---|---|---|
| Product: | Documentation | Reporter: | Michael Laß <bevan> |
| Component: | Books & Articles | Assignee: | freebsd-doc (Nobody) <doc> |
| Status: | Closed FIXED | ||
| Severity: | Affects Only Me | CC: | bcr |
| Priority: | --- | ||
| Version: | Latest | ||
| Hardware: | Any | ||
| OS: | Any | ||
A commit references this bug: Author: bcr Date: Mon May 13 15:57:12 UTC 2019 New revision: 53010 URL: https://svnweb.freebsd.org/changeset/doc/53010 Log: Correct the description of vfs.zfs.arc_max. Update the description of the default value for the vgs.zfs.arc_max tunable. It changed since the chapter was written and this patch updates it to the definition in the code. PR: 235543 Submitted by: bevan@bi-co.net Reviewed by: allanjude@ Changes: head/en_US.ISO8859-1/books/handbook/zfs/chapter.xml I just committed a patch with your suggested wording. Thanks for filing the PR, which is closed now. |
The description of the default value for vfs.zfs.arc_max in the handbook (section 19.6.1.) is inaccurate. I propose phrasing it as follows: "The default is all RAM but 1 GB, or 5/8 of all RAM, whichever is more." Here is the actual code defining these default in sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c: /* set min cache to 1/32 of all memory, or arc_abs_min, whichever is more */ arc_c_min = MAX(allmem / 32, arc_abs_min); /* set max to 5/8 of all memory, or all but 1GB, whichever is more */ if (allmem >= 1 << 30) arc_c_max = allmem - (1 << 30); else arc_c_max = arc_c_min; arc_c_max = MAX(allmem * 5 / 8, arc_c_max);