From d0fa75352b7ffd586499d28983bff5d714e5211a Mon Sep 17 00:00:00 2001 From: Markus Metzger Date: Wed, 10 Apr 2013 13:43:41 +0200 Subject: [PATCH] btrace: increase buffer size Try to allocate as much buffer as we can for each thread with a maximum of 64KB. 2014-01-16 Markus Metzger * common/linux-btrace.c (linux_enable_btrace): Enlarge buffer. --- gdb/ChangeLog | 4 ++++ gdb/common/linux-btrace.c | 25 +++++++++++++++---------- 2 files changed, 19 insertions(+), 10 deletions(-) diff --git a/gdb/ChangeLog b/gdb/ChangeLog index acd6b02d9f6..50c6bcd6988 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,7 @@ +2014-01-16 Markus Metzger + + * common/linux-btrace.c (linux_enable_btrace): Enlarge buffer. + 2014-01-16 Markus Metzger * btrace.c (ftrace_new_function): Start counting at one. diff --git a/gdb/common/linux-btrace.c b/gdb/common/linux-btrace.c index 54740494f2a..e469900def3 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: -- 2.30.2