From: Andreas Mohr During some performance diagnostics I stumbled on this slightly wasteful code in pcnet_cs.c which I made the patch included at the bottom for (two minor comment fixes included). Improvement: instead of *always* calculating lea 0x2c0(%edx),%ebx and then additionally doing the mov %edx,0xc0(%ebx) addition *if we need it*, we now do the *whole* calculation of mov %edx,0x380(%ebx) *only* if we need it. This even manages to save us a whole 16-byte alignment buffer loss in this compilation case. Result: slightly improves IRQ handler performance in both shared and non-shared IRQ case, which should make my rusty P3/700 a slight bit happier. Thank you for your support, Andreas Mohr old asm result (using gcc 3.3.5): 000015a0 : 15a0: 55 push %ebp 15a1: 89 e5 mov %esp,%ebp 15a3: 53 push %ebx 15a4: 8d 9a c0 02 00 00 lea 0x2c0(%edx),%ebx 15aa: e8 fc ff ff ff call 15ab 15af: 83 f8 01 cmp $0x1,%eax 15b2: 74 03 je 15b7 15b4: 5b pop %ebx 15b5: 5d pop %ebp 15b6: c3 ret 15b7: 31 d2 xor %edx,%edx 15b9: 89 93 c0 00 00 00 mov %edx,0xc0(%ebx) 15bf: eb f3 jmp 15b4 15c1: eb 0d jmp 15d0 15c3: 90 nop 15c4: 90 nop 15c5: 90 nop 15c6: 90 nop 15c7: 90 nop 15c8: 90 nop 15c9: 90 nop 15ca: 90 nop 15cb: 90 nop 15cc: 90 nop 15cd: 90 nop 15ce: 90 nop 15cf: 90 nop 000015d0 : new asm result: 000015a0 : 15a0: 55 push %ebp 15a1: 89 e5 mov %esp,%ebp 15a3: 53 push %ebx 15a4: 89 d3 mov %edx,%ebx 15a6: e8 fc ff ff ff call 15a7 15ab: 83 f8 01 cmp $0x1,%eax 15ae: 74 03 je 15b3 15b0: 5b pop %ebx 15b1: 5d pop %ebp 15b2: c3 ret 15b3: 31 d2 xor %edx,%edx 15b5: 89 93 80 03 00 00 mov %edx,0x380(%ebx) 15bb: eb f3 jmp 15b0 15bd: 8d 76 00 lea 0x0(%esi),%esi 000015c0 : Signed-off-by: Andrew Morton --- 25-akpm/drivers/net/pcmcia/pcnet_cs.c | 10 ++++++---- 1 files changed, 6 insertions(+), 4 deletions(-) diff -puN drivers/net/pcmcia/pcnet_cs.c~pcnet_csc-irq-handler-optimization drivers/net/pcmcia/pcnet_cs.c --- 25/drivers/net/pcmcia/pcnet_cs.c~pcnet_csc-irq-handler-optimization 2005-04-04 19:40:12.000000000 -0700 +++ 25-akpm/drivers/net/pcmcia/pcnet_cs.c 2005-04-04 19:40:12.000000000 -0700 @@ -1155,11 +1155,13 @@ static int set_config(struct net_device static irqreturn_t ei_irq_wrapper(int irq, void *dev_id, struct pt_regs *regs) { struct net_device *dev = dev_id; - pcnet_dev_t *info = PRIV(dev); + pcnet_dev_t *info; irqreturn_t ret = ei_interrupt(irq, dev_id, regs); - if (ret == IRQ_HANDLED) + if (ret == IRQ_HANDLED) { + info = PRIV(dev); info->stale = 0; + } return ret; } @@ -1350,7 +1352,7 @@ static void dma_block_input(struct net_d if (count & 0x01) buf[count-1] = inb(nic_base + PCNET_DATAPORT), xfer_count++; - /* This was for the ALPHA version only, but enough people have + /* This was for the ALPHA version only, but enough people have been encountering problems that it is still here. */ #ifdef PCMCIA_DEBUG if (ei_debug > 4) { /* DMA termination address check... */ @@ -1424,7 +1426,7 @@ static void dma_block_output(struct net_ dma_start = jiffies; #ifdef PCMCIA_DEBUG - /* This was for the ALPHA version only, but enough people have + /* This was for the ALPHA version only, but enough people have been encountering problems that it is still here. */ if (ei_debug > 4) { /* DMA termination address check... */ int addr, tries = 20; _