diff options
Diffstat (limited to 'gdb/common/linux-btrace.c')
| -rw-r--r-- | gdb/common/linux-btrace.c | 25 |
1 files changed, 15 insertions, 10 deletions
diff --git a/gdb/common/linux-btrace.c b/gdb/common/linux-btrace.c index 5474049..e469900 100644 --- a/gdb/common/linux-btrace.c +++ b/gdb/common/linux-btrace.c @@ -423,7 +423,7 @@ struct btrace_target_info * linux_enable_btrace (ptid_t ptid) { struct btrace_target_info *tinfo; - int pid; + int pid, pg; tinfo = xzalloc (sizeof (*tinfo)); tinfo->ptid = ptid; @@ -451,17 +451,22 @@ linux_enable_btrace (ptid_t ptid) if (tinfo->file < 0) goto err; - /* We hard-code the trace buffer size. - At some later time, we should make this configurable. */ - tinfo->size = 1; - tinfo->buffer = mmap (NULL, perf_event_mmap_size (tinfo), - PROT_READ, MAP_SHARED, tinfo->file, 0); - if (tinfo->buffer == MAP_FAILED) - goto err_file; + /* We try to allocate as much buffer as we can get. + We could allow the user to specify the size of the buffer, but then + we'd leave this search for the maximum buffer size to him. */ + for (pg = 4; pg >= 0; --pg) + { + /* The number of pages we request needs to be a power of two. */ + tinfo->size = 1 << pg; + tinfo->buffer = mmap (NULL, perf_event_mmap_size (tinfo), + PROT_READ, MAP_SHARED, tinfo->file, 0); + if (tinfo->buffer == MAP_FAILED) + continue; - return tinfo; + return tinfo; + } - err_file: + /* We were not able to allocate any buffer. */ close (tinfo->file); err: |