BC proc entries

User Beancounters Definition /proc/user_beancounters /proc/bc/ General information Units of measurement VSwap Parameters description Primary parameters numproc, numtcpsock, numothersock, vmguarpages Secondary parameters kmemsize, tcpsndbuf, tcprcvbuf, othersockbuf, dgramrcvbuf, oomguarpages, privvmpages Auxiliary parameters lockedpages, shmpages, physpages, numfile, numflock, numpty, numsiginfo, dcachesize, numiptent, swappages Internals User pages accounting RSS fractions accounting On-demand accounting UBC consistency Consistency formulae System-wide configuration vzubc(8) Configuration examples Basic Derived Intermediate configurations Tables List of parameters Parameter properties Consistency Config examples

This page describes proc interface of UBC subsystem.

Old interface

The old interface consisted of 2 (optionally 3) files:

/proc/user_beancounters

reveals an overall information about resource consumption of each beancounter in system; described here;

/proc/user_beancounters_sub

reveals information about all beancounters and sub-beancounters in system;

/proc/user_beancounters_debug

shows debugging information about each beancounter. Available if CONFIG_UBC_DEBUG_KMEM option is turned on. Information revealed includes the numbers of

1. objects charged from each slab;
2. pages charged;
3. vmalloc-ed pages;
4. page beancounters;
5. etc.

New interface

In new interface only /proc/user_beancounters entry is left for compatibility with old tools. New entries reside in /proc/bc directory. This directory also contains subdirectories for each beancounter in the system. E.g.

# ls /proc/bc/
0  ioacct_debug  resources
# vzctl  start 101
...
# ls /proc/bc
0  101  ioacct_debug  resources
# ls /proc/bc/101/
ioacct  kmem_debug  resources  vmaux

All new entries that are in /proc/bc shows some overall information about BC subsystem, while entries in /proc/bc/$BCID show per-beancounter info.

Existing general entries

/proc/bc/resources

This entry looks like old /proc/user_beancounters entry but

1. it doesn't contain “dummy” resources
2. if new resource is added to BC it will appear in this entry only

/proc/bc/$BCID/resources

This entry shows the same as /proc/bc/resources does but for $BCID beancounter only.

/proc/bc/$BCID/vmaux

This entry shows auxiliary resources used in VM accounting.

/proc/bc/$BCID/kmem_debug

This entry is available with CONFIG_UBC_DEBUG_KMEM option set and shows per-beancounter info that was in /proc/user_beancounters_debug before.

Other entries

The following subsystems add their own entries in /proc/bc and /proc/bc/$BCID:

• IO accounting

Kernel API

Subsystems may add its own entries in /proc/bc or /proc/bc/$BCID. To facilitate this the following API is used in BC sybsystem (declared in include/ub/proc.h).

struct proc_dir_entry *bc_proc_root

This is an entry that corresponds to /proc/bc directory. If a subsystem wishes to report some information that is not per-beancounter it may create entry using this as a parent.

struct bc_proc_entry;

This describes an entry that may show per-beancounter info. This looks like this:

struct bc_proc_entry {
        char *name;
        int (*show)(struct seq_file *, void *);
        struct bc_proc_entry *next;
};

• name is the entry name as it will appear in /proc/bc/$BCID
• show is a callback that is to fill info about particulat beancounter

void bc_register_proc_entry(struct bc_proc_entry *);

This call registers an entry that shows per-beancounter info.

The code that fills info about BC must look like this:

static int bc_my_show(struct seq_file *f, void *v)
{
        struct user_beancounter *ub;

        ub = seq_beancounter(f);
        /* dump info into f here */
        return 0;
}
...
static struct bc_proc_entry my_entry = {
        .name = "my_entry",
        .show = bc_my_show,
};

static int __init bc_my_init(void)
{
        bc_register_proc_entry(&my_entry);
        return 0;
}

late_initcall(bc_my_init);

Note: Due to limitations in single_open the struct user_beancounter pointer is not passed as void *v into showing function but must be obtained from seq_file with seq_beancounter