On Thu, 10 Feb 2022 09:47:52 +0100 Christophe Leroy <christophe.leroy@xxxxxxxxxx> wrote: > On a ppc32 build with CONFIG_CC_OPTIMISE_FOR_SIZE, > trace_trigger_soft_disabled() appears more than 50 times in vmlinux. > > That function is rather big for an inlined function, and > it doesn't benefit much from inlining as its only parameter > is a pointer to a struct in memory: The number of parameters is not the reason for it being inlined. It's in a *very* hot path, and a function call causes a noticeable performance hit. > > c003df60 <trace_trigger_soft_disabled>: > c003df60: 94 21 ff f0 stwu r1,-16(r1) > c003df64: 7c 08 02 a6 mflr r0 > c003df68: 90 01 00 14 stw r0,20(r1) > c003df6c: bf c1 00 08 stmw r30,8(r1) > c003df70: 83 e3 00 24 lwz r31,36(r3) > c003df74: 73 e9 01 00 andi. r9,r31,256 > c003df78: 41 82 00 10 beq c003df88 <trace_trigger_soft_disabled+0x28> > c003df7c: 38 60 00 00 li r3,0 > c003df80: 39 61 00 10 addi r11,r1,16 > c003df84: 4b fd 60 ac b c0014030 <_rest32gpr_30_x> > c003df88: 73 e9 00 80 andi. r9,r31,128 > c003df8c: 7c 7e 1b 78 mr r30,r3 > c003df90: 41 a2 00 14 beq c003dfa4 <trace_trigger_soft_disabled+0x44> > c003df94: 38 c0 00 00 li r6,0 > c003df98: 38 a0 00 00 li r5,0 > c003df9c: 38 80 00 00 li r4,0 > c003dfa0: 48 05 c5 f1 bl c009a590 <event_triggers_call> > c003dfa4: 73 e9 00 40 andi. r9,r31,64 > c003dfa8: 40 82 00 28 bne c003dfd0 <trace_trigger_soft_disabled+0x70> > c003dfac: 73 ff 02 00 andi. r31,r31,512 > c003dfb0: 41 82 ff cc beq c003df7c <trace_trigger_soft_disabled+0x1c> > c003dfb4: 80 01 00 14 lwz r0,20(r1) > c003dfb8: 83 e1 00 0c lwz r31,12(r1) > c003dfbc: 7f c3 f3 78 mr r3,r30 > c003dfc0: 83 c1 00 08 lwz r30,8(r1) > c003dfc4: 7c 08 03 a6 mtlr r0 > c003dfc8: 38 21 00 10 addi r1,r1,16 > c003dfcc: 48 05 6f 6c b c0094f38 <trace_event_ignore_this_pid> > c003dfd0: 38 60 00 01 li r3,1 > c003dfd4: 4b ff ff ac b c003df80 <trace_trigger_soft_disabled+0x20> > > It doesn't benefit much from inlining as its only parameter is a > pointer to a struct in memory so no constant folding is involved. > > Uninline it and move it into kernel/trace/trace_events_trigger.c > > It reduces the size of vmlinux by approximately 10 kbytes. If you have an issue with the size, perhaps the function can be modified to condense it. I'm happy to have a size reduction, but I will NACK making it into a function call. -- Steve
