If you change the fprintf(pc->saved_fp, buf); lines to print_verbatim(pc->saved_fp, buf); Then I won't get: crash> sk_buff.head ffff88012014dc80 Segmentation fault When I need to get: crash> sk_buff.head ffff88012014dc80 head = 0xffff880121267000 "\"%s %s %s\", got type \"%s\"" Patch attached (6.0.8). I suspect performance will suffer a bit when I try to print 2 million of these...

----- Original Message ----- > On Thu, 2012-08-09 at 16:23 -0600, Bob Montgomery wrote: > > If you change the > > fprintf(pc->saved_fp, buf); > > lines to > > print_verbatim(pc->saved_fp, buf); > > > > Then I won't get: > > > > crash> sk_buff.head ffff88012014dc80 > > Segmentation fault > > > > When I need to get: > > > > crash> sk_buff.head ffff88012014dc80 > > head = 0xffff880121267000 "\"%s %s %s\", got type \"%s\"" > > > > > > Patch attached (6.0.8). > > > > I suspect performance will suffer a bit when I try to print > > 2 million of these... > > Wonder if it would be quicker on average to string search for "%" and > conditionally call print_verbatim??? I had lots of successful > fprintf's and only a small number of seg viol cases. > > Bob M. Hi Bob, Although in practice, (1) parse_for_member() is rarely called "in quantity", and (2) when it is called, it would only encounter this with "char *" members, and (3) the string would also have to have a '%' in it. On the other hand, if you test the two print-types with a million calls, there's a significant performance hit. But if a strstr() is done first on the string, there's virtually no hit at all if there's no '%' in it. So yes, I agree with you that the string-search/conditional call should be done. I'll add that to your patch, and queue it for crash-6.0.9. Thanks, Dave -- Crash-utility mailing list Crash-utility(a)redhat.com https://www.redhat.com/mailman/listinfo/crash-utility

----- Original Message ----- > What about replacing that fprintf() with fprintf(pc->saved_fp, "%s", buf) > or even fputs(buf, pc->saved_fp)? Hmmm, that would be preferable -- let me test that...

> On Fri, Aug 10, 2012 at 2:55 PM, Dave Anderson > <anderson(a)redhat.com&gt; > wrote: > > > > > > ----- Original Message ----- > >> On Thu, 2012-08-09 at 16:23 -0600, Bob Montgomery wrote: > >> > If you change the > >> > fprintf(pc->saved_fp, buf); > >> > lines to > >> > print_verbatim(pc->saved_fp, buf); > >> > > >> > Then I won't get: > >> > > >> > crash> sk_buff.head ffff88012014dc80 > >> > Segmentation fault > >> > > >> > When I need to get: > >> > > >> > crash> sk_buff.head ffff88012014dc80 > >> > head = 0xffff880121267000 "\"%s %s %s\", got type \"%s\"" > >> > > >> > > >> > Patch attached (6.0.8). > >> > > >> > I suspect performance will suffer a bit when I try to print > >> > 2 million of these... > >> > >> Wonder if it would be quicker on average to string search for > >> "%" > >> and > >> conditionally call print_verbatim??? I had lots of successful > >> fprintf's and only a small number of seg viol cases. > >> > >> Bob M. > > > > Hi Bob, > > > > Although in practice, > > > > (1) parse_for_member() is rarely called "in quantity", and > > (2) when it is called, it would only encounter this with "char > > *" > > members, and > > (3) the string would also have to have a '%' in it. > > > > On the other hand, if you test the two print-types with a million > > calls, > > there's a significant performance hit. But if a strstr() is done > > first > > on the string, there's virtually no hit at all if there's no '%' > > in > > it. > > > > So yes, I agree with you that the string-search/conditional call > > should be done. > > I'll add that to your patch, and queue it for crash-6.0.9. > > > > Thanks, > > Dave > > > > -- > > Crash-utility mailing list > > Crash-utility(a)redhat.com > > https://www.redhat.com/mailman/listinfo/crash-utility > > -- > Crash-utility mailing list > Crash-utility(a)redhat.com > https://www.redhat.com/mailman/listinfo/crash-utility >