Since Linux v3.4 (specifically, commit 438ced1720b584000 "ring-buffer: Add per_cpu ring buffer control files"), the trace buffer size is now per-cpu. The patch below updates the trace extension to handle this. Rabin diff --git a/extensions/trace.c b/extensions/trace.c index 831cc77..224c662 100644 --- a/extensions/trace.c +++ b/extensions/trace.c @@ -24,6 +24,7 @@ static int nr_cpu_ids; * lockless ring_buffer and old non-lockless ring_buffer are both supported. */ static int lockless_ring_buffer; +static int per_cpu_buffer_sizes; #define koffset(struct, member) struct##_##member##_offset @@ -37,6 +38,7 @@ static int koffset(ring_buffer, buffers); static int koffset(ring_buffer_per_cpu, cpu); static int koffset(ring_buffer_per_cpu, pages); +static int koffset(ring_buffer_per_cpu, nr_pages); static int koffset(ring_buffer_per_cpu, head_page); static int koffset(ring_buffer_per_cpu, tail_page); static int koffset(ring_buffer_per_cpu, commit_page); @@ -71,6 +73,7 @@ struct ring_buffer_per_cpu { ulong real_head_page; int head_page_index; + unsigned int nr_pages; ulong *pages; ulong *linear_pages; @@ -144,7 +147,14 @@ static int init_offsets(void) init_offset(trace_array, buffer); init_offset(tracer, name); - init_offset(ring_buffer, pages); + if (MEMBER_EXISTS("ring_buffer_per_cpu", "nr_pages")) { + per_cpu_buffer_sizes = 1; + if (verbose) + fprintf(fp, "per cpu buffer sizes\n"); + } + + if (!per_cpu_buffer_sizes) + init_offset(ring_buffer, pages); init_offset(ring_buffer, flags); init_offset(ring_buffer, cpus); init_offset(ring_buffer, buffers); @@ -155,6 +165,8 @@ static int init_offsets(void) fprintf(fp, "lockless\n"); } + if (per_cpu_buffer_sizes) + init_offset(ring_buffer_per_cpu, nr_pages); init_offset(ring_buffer_per_cpu, cpu); init_offset(ring_buffer_per_cpu, pages); init_offset(ring_buffer_per_cpu, head_page); @@ -362,6 +374,10 @@ static int ftrace_init_buffers(struct ring_buffer_per_cpu *buffers, buffer_read_value(reader_page); buffer_read_value(overrun); buffer_read_value(entries); + if (per_cpu_buffer_sizes) { + buffer_read_value(nr_pages); + pages = buffers[i].nr_pages; + } #undef buffer_read_value if (ftrace_init_pages(buffers + i, pages) < 0) -- 1.7.9.5