Messages in this thread | | | Date | Thu, 13 Nov 2014 17:08:33 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH 02/10] perf, tools: Support handling complete branch stacks as histograms |
| |
Em Thu, Nov 13, 2014 at 08:52:08PM +0100, Andi Kleen escreveu: > On Thu, Nov 13, 2014 at 04:14:17PM -0300, Arnaldo Carvalho de Melo wrote: > > Em Wed, Nov 12, 2014 at 06:05:20PM -0800, Andi Kleen escreveu: > > > +static int remove_loops(struct branch_entry *l, int nr) > > > +{ > > > + int i, j, off; > > > + unsigned char chash[CHASHSZ]; > > > + > > > + memset(chash, NO_ENTRY, sizeof(chash)); > > > + > > > + BUG_ON(nr >= 256); > > > > What is wrong with return -1 and propagating the error, so that the user > > is informed if the data being processed is bogus, stop processing with a > > warning or continue processing if finding the next valid record is > > possible? > > The error doesn't depend on the record. There is a check for the record > being < 127 in front of this. This is merely to catch that > if someone increases PERF_MAX_BRANCH_DEPTH to below 255 they need > to increase the type of the hash table from u8.
Ok, so this would be better as a BUILD_BUG_ON?
Like:
#define CHASHSZ 127 #define CHASHBITS 7 #define NO_ENTRY 0xff
#define PERF_MAX_BRANCH_DEPTH 127
/* Remove loops. */ static int remove_loops(struct branch_entry *l, int nr) { int i, j, off; unsigned char chash[CHASHSZ];
memset(chash, NO_ENTRY, sizeof(chash));
/* Change the type of the chash table, u8 is not enough now */ BUILD_BUG_ON(PERF_MAX_BRANCH_DEPTH >= 256); for (i = 0; i < nr; i++) { int h = hash_64(l[i].from, CHASHBITS) % CHASHSZ;
-------------------------------------
- Arnaldo
| |