| Message ID | 3b651381f4c53988ede62f4a1505e7e8ccab56b4.1648131740.git.christophe.leroy@csgroup.eu (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | powerpc: ftrace optimisation and cleanup and more [v1] | expand |
Christophe Leroy wrote: > Inlining ftrace_modify_code(), it increases a bit the > size of ftrace code but brings 5% improvment on ftrace > activation. > > Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> > --- > arch/powerpc/kernel/trace/ftrace.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/powerpc/kernel/trace/ftrace.c b/arch/powerpc/kernel/trace/ftrace.c > index 41c45b9c7f39..98e82fa4980f 100644 > --- a/arch/powerpc/kernel/trace/ftrace.c > +++ b/arch/powerpc/kernel/trace/ftrace.c > @@ -53,7 +53,7 @@ ftrace_call_replace(unsigned long ip, unsigned long addr, int link) > return op; > } > > -static int > +static inline int > ftrace_modify_code(unsigned long ip, ppc_inst_t old, ppc_inst_t new) > { > ppc_inst_t replaced; I thought gcc was free to inline functions without the need for 'inline'. Don't you see this being inlined otherwise? On the flip side, don't we need __always_inline if we want to force inlining? - Naveen
"Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com> writes: > Christophe Leroy wrote: >> Inlining ftrace_modify_code(), it increases a bit the >> size of ftrace code but brings 5% improvment on ftrace >> activation. >> >> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> >> --- >> arch/powerpc/kernel/trace/ftrace.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/arch/powerpc/kernel/trace/ftrace.c b/arch/powerpc/kernel/trace/ftrace.c >> index 41c45b9c7f39..98e82fa4980f 100644 >> --- a/arch/powerpc/kernel/trace/ftrace.c >> +++ b/arch/powerpc/kernel/trace/ftrace.c >> @@ -53,7 +53,7 @@ ftrace_call_replace(unsigned long ip, unsigned long addr, int link) >> return op; >> } >> >> -static int >> +static inline int >> ftrace_modify_code(unsigned long ip, ppc_inst_t old, ppc_inst_t new) >> { >> ppc_inst_t replaced; > > I thought gcc was free to inline functions without the need for > 'inline'. Yes it is. > On the flip side, don't we need __always_inline if we want to force > inlining? Yes. Since ac7c3e4ff401 ("compiler: enable CONFIG_OPTIMIZE_INLINING forcibly"). cheers
Le 18/04/2022 à 08:07, Naveen N. Rao a écrit : > Christophe Leroy wrote: >> Inlining ftrace_modify_code(), it increases a bit the >> size of ftrace code but brings 5% improvment on ftrace >> activation. >> >> Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> >> --- >> arch/powerpc/kernel/trace/ftrace.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/arch/powerpc/kernel/trace/ftrace.c >> b/arch/powerpc/kernel/trace/ftrace.c >> index 41c45b9c7f39..98e82fa4980f 100644 >> --- a/arch/powerpc/kernel/trace/ftrace.c >> +++ b/arch/powerpc/kernel/trace/ftrace.c >> @@ -53,7 +53,7 @@ ftrace_call_replace(unsigned long ip, unsigned long >> addr, int link) >> return op; >> } >> >> -static int >> +static inline int >> ftrace_modify_code(unsigned long ip, ppc_inst_t old, ppc_inst_t new) >> { >> ppc_inst_t replaced; > > I thought gcc was free to inline functions without the need for > 'inline'. Don't you see this being inlined otherwise? Yep, gcc is free to inline, but in that case it doesn't inline unless you suggest it to do so. > > On the flip side, don't we need __always_inline if we want to force > inlining? The question is, do we want to force inlining, even with CONFIG_CC_OPTIMIZE_FOR_SIZE ? With 'inline', gcc seems to now inline it with CONFIG_CC_OPTIMIZE_FOR_SPEED and still keep it out of line with CONFIG_CC_OPTIMIZE_FOR_SIZE. Christophe
diff --git a/arch/powerpc/kernel/trace/ftrace.c b/arch/powerpc/kernel/trace/ftrace.c index 41c45b9c7f39..98e82fa4980f 100644 --- a/arch/powerpc/kernel/trace/ftrace.c +++ b/arch/powerpc/kernel/trace/ftrace.c @@ -53,7 +53,7 @@ ftrace_call_replace(unsigned long ip, unsigned long addr, int link) return op; } -static int +static inline int ftrace_modify_code(unsigned long ip, ppc_inst_t old, ppc_inst_t new) { ppc_inst_t replaced;
Inlining ftrace_modify_code(), it increases a bit the size of ftrace code but brings 5% improvment on ftrace activation. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> --- arch/powerpc/kernel/trace/ftrace.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)