[PATCH v5 4/6] perf tools: Show memory region in perf-c2c subcommand
From: Thomas Falcon
Date: Thu Aug 20 2026 - 20:18:53 EST
From: Dapeng Mi <dapeng1.mi@xxxxxxxxxxxxxxx>
Add memory region field to the cacheline list view to help users
identify the memory region to which the cacheline belongs. The memory
region field was included with the introduction of support for the
Off-module Response facility (OMR) [1] in Intel's Diamond Rapids and
Nova Lake architectures.
An example of the new perf c2c output including the memory region
field is shown below:
Shared Data Cache Line Table (112 entries, sorted on Total HITMs)
--------------- Cacheline -------------- Tot ------- Load Hitm ------- Total Total Total
Index Address Region Node PA cnt Hitm Total LclHitm RmtHitm records Loads Stores
0 0xff1b7032a1e8c5c0 N/A 1 47 2.25% 50 44 6 1024 1023 1
1 0xff1b6ff3255bb880 N/A 0 11 1.62% 36 34 2 96 93 4
2 0xff1b70328e3b9880 N/A 1 13 1.49% 33 33 0 100 91 9
3 0xff1b70328b023800 N/A 1 1 1.40% 31 14 17 52 48 4
4 0xff1b70328e3b9c00 N/A 1 1 1.31% 29 27 2 67 33 34
5 0xff1b70328b0237c0 N/A 1 1 1.26% 28 10 18 154 150 4
6 0xff1b6ff3255bbc00 N/A 0 1 1.13% 25 25 0 48 25 23
7 0xff1b6ff3255bba40 N/A 0 1 0.99% 22 22 0 46 23 23
8 0xff3ab9ba50255c80 N/A N/A 0 0.77% 17 15 2 35 35 0
9 0xff3ab9ba503e3040 N/A N/A 0 0.77% 17 11 6 37 37 1
10 0xff1b703289e88f40 N/A 1 33 0.72% 16 9 7 69 63 6
11 0xff1b70328e3b9a40 N/A 1 1 0.68% 15 15 0 43 17 26
12 0xff1b7032c9fd6a40 N/A 1 15 0.68% 15 15 0 57 54 4
13 0xff1b7032a1e8c980 N/A 1 27 0.54% 12 11 1 761 761 0
14 0xff1b70727ffd57c0 N/A 1 7 0.54% 12 12 0 219 218 1
15 0xffffffffaefe2380 N/A 1 1 0.50% 11 8 3 14 14 0
Note: DMR simics does not support memory regions. Since the output is
captured on SPR, the memory region field shows "N/A" for all cachelines.
[1]: https://lore.kernel.org/all/20260114011750.350569-1-dapeng1.mi@xxxxxxxxxxxxxxx/
Assisted-by: Sashiko:gemini-3.1-pro-preview
Assisted-by: GitHub-Copilot:claude-opus-4-8
Reviewed-by: Ian Rogers <irogers@xxxxxxxxxx>
Signed-off-by: Dapeng Mi <dapeng1.mi@xxxxxxxxxxxxxxx>
Signed-off-by: Thomas Falcon <thomas.falcon@xxxxxxxxx>
---
v5: make the cacheline header span and ui_quirks() width
fixup depend on memory-region availability (Namhyung Kim)
v4: correctly handle output_str memory allocation failure
v3: make memory region reporting conditional on feature bit
---
tools/perf/builtin-c2c.c | 95 ++++++++++++++++++++++++++++++++++++----
1 file changed, 86 insertions(+), 9 deletions(-)
diff --git a/tools/perf/builtin-c2c.c b/tools/perf/builtin-c2c.c
index bc16a57e0927..ce324fc59947 100644
--- a/tools/perf/builtin-c2c.c
+++ b/tools/perf/builtin-c2c.c
@@ -77,6 +77,7 @@ struct c2c_hist_entry {
unsigned long *nodeset;
struct c2c_stats *node_stats;
unsigned int cacheline_idx;
+ unsigned int mem_region;
struct compute_stats cstats;
@@ -107,6 +108,7 @@ struct perf_c2c {
bool show_src;
bool show_all;
+ bool show_mem_region;
bool use_stdio;
bool stats_only;
bool symbol_full;
@@ -283,6 +285,18 @@ static void c2c_he__set_node(struct c2c_hist_entry *c2c_he,
}
}
+static void c2c_he__set_mem_region(struct c2c_hist_entry *c2c_he,
+ unsigned int mem_region)
+{
+ if (WARN_ONCE(mem_region > PERF_MEM_REGION_MEM7,
+ "WARNING: invalid memory region ID\n"))
+ return;
+
+ /* Update mem_region only if it really accesses memory */
+ if (mem_region >= PERF_MEM_REGION_MMIO)
+ c2c_he->mem_region = mem_region;
+}
+
static void compute_stats(struct c2c_hist_entry *c2c_he,
struct c2c_stats *stats,
u64 weight)
@@ -341,6 +355,7 @@ static int process_sample_event(const struct perf_tool *tool __maybe_unused,
struct addr_location al;
struct mem_info *mi = NULL;
struct callchain_cursor *cursor;
+ unsigned int mem_region;
int ret;
addr_location__init(&al);
@@ -368,6 +383,7 @@ static int process_sample_event(const struct perf_tool *tool __maybe_unused,
}
c2c_decode_stats(&stats, mi);
+ mem_region = mem_info__data_src(mi)->mem_region;
he = hists__add_entry_ops(&c2c_hists->hists, &c2c_entry_ops,
&al, NULL, NULL, mi, NULL,
@@ -384,6 +400,7 @@ static int process_sample_event(const struct perf_tool *tool __maybe_unused,
c2c_he__set_cpu(c2c_he, sample);
c2c_he__set_node(c2c_he, sample);
c2c_he__set_evsel(c2c_he, evsel);
+ c2c_he__set_mem_region(c2c_he, mem_region);
hists__inc_nr_samples(&c2c_hists->hists, he->filtered);
@@ -437,6 +454,7 @@ static int process_sample_event(const struct perf_tool *tool __maybe_unused,
c2c_he__set_cpu(c2c_he, sample);
c2c_he__set_node(c2c_he, sample);
c2c_he__set_evsel(c2c_he, evsel);
+ c2c_he__set_mem_region(c2c_he, mem_region);
hists__inc_nr_samples(&c2c_hists->hists, he->filtered);
ret = hist_entry__append_callchain(he, sample);
@@ -605,6 +623,30 @@ dcacheline_node_count(struct perf_hpp_fmt *fmt, struct perf_hpp *hpp,
return scnprintf(hpp->buf, hpp->size, "%*lu", width, c2c_he->paddr_cnt);
}
+static int
+dcacheline_node_mem_region(struct perf_hpp_fmt *fmt, struct perf_hpp *hpp,
+ struct hist_entry *he)
+{
+ int width = c2c_width(fmt, hpp, he->hists);
+ struct c2c_hist_entry *c2c_he;
+ unsigned int mem_region;
+ char buf[20];
+
+ c2c_he = container_of(he, struct c2c_hist_entry, he);
+ mem_region = c2c_he->mem_region;
+
+ if (mem_region == PERF_MEM_REGION_NA)
+ scnprintf(buf, sizeof(buf), "N/A");
+ /* mem_region could only be >= PERF_MEM_REGION_MMIO */
+ else if (mem_region == PERF_MEM_REGION_MMIO)
+ scnprintf(buf, sizeof(buf), "MMIO");
+ else
+ scnprintf(buf, sizeof(buf), "0x%x",
+ mem_region - PERF_MEM_REGION_MEM0);
+
+ return scnprintf(hpp->buf, hpp->size, "%*s", width, buf);
+}
+
static int offset_entry(struct perf_hpp_fmt *fmt, struct perf_hpp *hpp,
struct hist_entry *he)
{
@@ -1442,6 +1484,14 @@ static struct c2c_dimension dim_dcacheline_node = {
.width = 4,
};
+static struct c2c_dimension dim_dcacheline_mem_region = {
+ .header = HEADER_LOW("Region"),
+ .name = "dcacheline_mem_region",
+ .cmp = empty_cmp,
+ .entry = dcacheline_node_mem_region,
+ .width = 6,
+};
+
static struct c2c_dimension dim_dcacheline_count = {
.header = HEADER_LOW("PA cnt"),
.name = "dcacheline_count",
@@ -1873,6 +1923,7 @@ static struct c2c_dimension dim_dcacheline_num_empty = {
static struct c2c_dimension *dimensions[] = {
&dim_dcacheline,
+ &dim_dcacheline_mem_region,
&dim_dcacheline_node,
&dim_dcacheline_count,
&dim_offset,
@@ -2942,8 +2993,11 @@ static int ui_quirks(void)
/* Fix the zero line for dcacheline column. */
buf = fill_line(chk_double_cl ? "Double-Cacheline" : "Cacheline",
dim_dcacheline.width +
+ (c2c.show_mem_region ?
+ dim_dcacheline_mem_region.width : 0) +
dim_dcacheline_node.width +
- dim_dcacheline_count.width + 4);
+ dim_dcacheline_count.width +
+ (c2c.show_mem_region ? 6 : 4));
if (!buf)
return -ENOMEM;
@@ -3195,7 +3249,8 @@ static int perf_c2c__report(int argc, const char **argv)
OPT_END()
};
int err = 0;
- const char *output_str, *sort_str = NULL;
+ const char *sort_str = NULL;
+ char *output_str = NULL;
struct perf_env *env;
annotation_options__init();
@@ -3360,9 +3415,16 @@ static int perf_c2c__report(int argc, const char **argv)
goto out_mem2node;
}
- if (c2c.display != DISPLAY_SNP_PEER)
- output_str = "cl_idx,"
+ c2c.show_mem_region = perf_header__has_feat(&session->header,
+ HEADER_MEMORY_RANGES);
+ if (c2c.show_mem_region)
+ dim_dcacheline.header.line[0].span = 3;
+
+ if (c2c.display != DISPLAY_SNP_PEER) {
+ if (asprintf(&output_str,
+ "cl_idx,"
"dcacheline,"
+ "%s"
"dcacheline_node,"
"dcacheline_count,"
"percent_costly_snoop,"
@@ -3374,10 +3436,17 @@ static int perf_c2c__report(int argc, const char **argv)
"ld_fbhit,ld_l1hit,ld_l2hit,"
"ld_lclhit,lcl_hitm,"
"ld_rmthit,rmt_hitm,"
- "dram_lcl,dram_rmt";
- else
- output_str = "cl_idx,"
+ "dram_lcl,dram_rmt",
+ c2c.show_mem_region ?
+ "dcacheline_mem_region," : "") < 0) {
+ err = -ENOMEM;
+ goto out_mem2node;
+ }
+ } else {
+ if (asprintf(&output_str,
+ "cl_idx,"
"dcacheline,"
+ "%s"
"dcacheline_node,"
"dcacheline_count,"
"percent_costly_snoop,"
@@ -3389,7 +3458,13 @@ static int perf_c2c__report(int argc, const char **argv)
"ld_fbhit,ld_l1hit,ld_l2hit,"
"ld_lclhit,lcl_hitm,"
"ld_rmthit,rmt_hitm,"
- "dram_lcl,dram_rmt";
+ "dram_lcl,dram_rmt",
+ c2c.show_mem_region ?
+ "dcacheline_mem_region," : "") < 0) {
+ err = -ENOMEM;
+ goto out_mem2node;
+ }
+ }
if (c2c.display == DISPLAY_TOT_HITM)
sort_str = "tot_hitm";
@@ -3418,11 +3493,13 @@ static int perf_c2c__report(int argc, const char **argv)
if (ui_quirks()) {
pr_err("failed to setup UI\n");
- goto out_mem2node;
+ goto out_str;
}
perf_c2c_display(session);
+out_str:
+ free(output_str);
out_mem2node:
mem2node__exit(&c2c.mem2node);
out_session:
--
2.55.0