[Crash-utility] [PATCH] kmem: Add support to -S option to specify a range of CPU-specific slab data
HAGIO KAZUHITO(萩尾 一仁)
k-hagio-ab at nec.com
Thu Jul 8 08:54:11 UTC 2021
-----Original Message-----
> With this patch, it is now possible for one to explicitly specify a range
> of CPU-specific slab data to list. For example:
Thanks for the patch, that is useful.
>
> Note: This is only applicable to a Linux kernel with Kconfig
> CONFIG_SLUB enabled. The optional argument GNU extension
> for getopt(3) is utilised; and, the CPU range must be
> specified as expected
>
> crash> kmem -S=1,4 kmalloc-512
> CACHE OBJSIZE ALLOCATED TOTAL SLABS SSIZE NAME
> ffff8d3f07c06c00 512 1916 3680 115 16k kmalloc-512
> CPU 1 KMEM_CACHE_CPU:
> ffff8d461fa6f140
> CPU 1 SLAB:
> SLAB MEMORY NODE TOTAL ALLOCATED FREE
> fffff540df7c4000 ffff8d45df100000 0 32 8 24
> FREE / [ALLOCATED]
> ffff8d45df100000 (cpu 1 cache)
> [ffff8d45df100200]
> ffff8d45df100400 (cpu 1 cache)
> [ffff8d45df100600]
> ffff8d45df100800 (cpu 1 cache)
> ffff8d45df100a00 (cpu 1 cache)
> ffff8d45df100c00 (cpu 1 cache)
> ffff8d45df100e00 (cpu 1 cache)
> ffff8d45df101000 (cpu 1 cache)
> [ffff8d45df101200]
> ...skipped ...
> CPU 4 KMEM_CACHE_CPU:
> ffff8d461fb2f140
> CPU 4 SLAB:
> SLAB MEMORY NODE TOTAL ALLOCATED FREE
> fffff540dfde3800 ffff8d45f78e0000 0 32 8 24
> FREE / [ALLOCATED]
> [ffff8d45f78e0000]
> ffff8d45f78e0200 (cpu 4 cache)
> ffff8d45f78e0400 (cpu 4 cache)
> [ffff8d45f78e0600]
> ffff8d45f78e0800 (cpu 4 cache)
> ffff8d45f78e0a00 (cpu 4 cache)
> ffff8d45f78e0c00 (cpu 4 cache)
> ffff8d45f78e0e00 (cpu 4 cache)
> ffff8d45f78e1000 (cpu 4 cache)
> ffff8d45f78e1200 (cpu 4 cache)
> ffff8d45f78e1400 (cpu 4 cache)
> [ffff8d45f78e1600]
> ...skipped ...
>
> Signed-off-by: Aaron Tomlin <atomlin at redhat.com>
> ---
> help.c | 5 ++++-
> memory.c | 47 +++++++++++++++++++++++++++++++++++++++++++----
> 2 files changed, 47 insertions(+), 5 deletions(-)
>
> diff --git a/help.c b/help.c
> index e0c8408..8d40204 100644
> --- a/help.c
> +++ b/help.c
> @@ -6571,7 +6571,7 @@ char *help_kmem[] = {
> "kmem",
> "kernel memory",
> "[-f|-F|-c|-C|-i|-v|-V|-n|-z|-o|-h] [-p | -m member[,member]]\n"
> -" [[-s|-S|-r] [slab] [-I slab[,slab]]] [-g [flags]] [[-P] address]]",
> +" [[-s|-S|-S=cpu[s]|-r] [slab] [-I slab[,slab]]] [-g [flags]] [[-P] address]]",
> " This command displays information about the use of kernel memory.\n",
> " -f displays the contents of the system free memory headers.",
> " also verifies that the page count equals nr_free_pages.",
> @@ -6616,6 +6616,9 @@ char *help_kmem[] = {
> " slab data for each per-cpu slab is displayed, along with the",
> " address of each kmem_cache_node, its count of full and partial",
> " slabs, and a list of all tracked slabs.",
> +" Note: one can specify the per-cpu slab data to be displayed;",
> +" the cpu[s] can be given as \"1,3,5\", \"1-3\", \"1,3,5-7,10\",",
> +" \"all\", or \"a\" (shortcut for \"all\").",
> " -r displays the accumulated basic kmalloc() slab data of each",
> " root slab cache and its children. The kernel must contain the",
> " \"slab_root_caches\" list_head. (currently only available if",
> diff --git a/memory.c b/memory.c
> index 8c6bbe4..ef7c3ec 100644
> --- a/memory.c
> +++ b/memory.c
> @@ -47,6 +47,7 @@ struct meminfo { /* general purpose memory information structure */
> int slab_offset;
> char *reqname;
> char *curname;
> + ulong *spec_cpumask;
> ulong *addrlist;
> int *kmem_bufctl;
> ulong *cpudata[NR_CPUS];
> @@ -4850,10 +4851,13 @@ cmd_kmem(void)
> struct meminfo meminfo;
> ulonglong value[MAXARGS];
> char buf[BUFSIZE];
> + char arg_buf[BUFSIZE];
> char *p1;
> - int spec_addr, escape;
> + ulong *cpus;
> + int spec_addr, escape, choose_cpu;
>
> - spec_addr = 0;
> + cpus = NULL;
> + spec_addr = choose_cpu = 0;
> sflag = Sflag = pflag = fflag = Fflag = Pflag = zflag = oflag = 0;
> vflag = Cflag = cflag = iflag = nflag = lflag = Lflag = Vflag = 0;
> gflag = hflag = rflag = 0;
> @@ -4862,7 +4866,7 @@ cmd_kmem(void)
> BZERO(&value[0], sizeof(ulonglong)*MAXARGS);
> pc->curcmd_flags &= ~HEADER_PRINTED;
>
> - while ((c = getopt(argcnt, args, "gI:sSrFfm:pvczCinl:L:PVoh")) != EOF) {
> + while ((c = getopt(argcnt, args, "gI:sS::rFfm:pvczCinl:L:PVoh")) != EOF) {
> switch(c)
> {
> case 'V':
> @@ -4902,6 +4906,33 @@ cmd_kmem(void)
> break;
>
> case 'S':
> + if (choose_cpu)
> + error(FATAL, "only one -S option allowed\n");
> + /* Use the GNU extension with getopt(3) ... */
> + if (optarg) {
> + if (!(vt->flags & KMALLOC_SLUB))
> + error(FATAL,
> + "can only use -S=cpu(s) with a kernel \n"
> + "that is built with CONFIG_SLUB support.\n");
> + if (optarg[0] != '=')
> + error(FATAL,
> + "CPU-specific slab data to be displayed "
> + "must be written as expected only e.g. -S=1,45.\n");
> + /* Skip = ... */
> + optarg++;
> +
> + choose_cpu = 1;
> + BZERO(arg_buf, BUFSIZE);
> + strcpy(arg_buf, optarg);
> +
> + cpus = get_cpumask_buf();
> + make_cpumask(arg_buf, cpus, FAULT_ON_ERROR, NULL);
> + meminfo.spec_cpumask = cpus;
> +
> + for (i = 0; i < kt->cpus; i++)
> + if (NUM_IN_BITMAP(cpus, i) && check_offline_cpu(i))
> + error(INFO, "CPU %d is OFFLINE.\n", i);
By default, crash commands do not print this message for offline cpus,
it is printed only with the offline hide option:
crash> bt -c 15
PID: 0 TASK: ffff916041651840 CPU: 15 COMMAND: "swapper/15"
...
crash> set offline hide
offline: hide
crash> bt -c 15
bt: CPU 15 is OFFLINE.
But ...
> + }
> Sflag = 1; sflag = rflag = 0;
> break;
>
> @@ -5184,6 +5215,8 @@ cmd_kmem(void)
> meminfo.flags = VERBOSE;
> vt->dump_kmem_cache(&meminfo);
> }
> + if (choose_cpu)
> + FREEBUF(cpus);
> }
>
> if (vflag == 1)
> @@ -19079,7 +19112,13 @@ do_kmem_cache_slub(struct meminfo *si)
> per_cpu = (ulong *)GETBUF(sizeof(ulong) * vt->numnodes);
>
> for (i = 0; i < kt->cpus; i++) {
> - if (hide_offline_cpu(i)) {
> + if (si->spec_cpumask) {
> + if (!(NUM_IN_BITMAP(si->spec_cpumask, i)))
> + continue;
> + else
> + if (check_offline_cpu(i))
> + continue;
> + } else if (hide_offline_cpu(i)) {
> fprintf(fp, "CPU %d [OFFLINE]\n", i);
> continue;
> }
the kmem -S already follows the hide option in this way.
So would you remove the "CPU xx is OFFLINE" message above and
change this hunk like this?
for (i = 0; i < kt->cpus; i++) {
+ if (si->spec_cpumask && !NUM_IN_BITMAP(si->spec_cpumask, i))
+ continue;
+
if (hide_offline_cpu(i)) {
fprintf(fp, "CPU %d [OFFLINE]\n", i);
continue;
}
Thanks,
Kazu
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