linux-kernel - Re: [PATCH] net/smc: Reduce size of smc_wr_tx_tasklet

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Message-ID: <20250317013428.GC56800@linux.alibaba.com>
Date: Mon, 17 Mar 2025 09:34:28 +0800
From: Dust Li <dust.li@...ux.alibaba.com>
To: I Hsin Cheng <richard120310@...il.com>, alibuda@...ux.alibaba.com
Cc: wenjia@...ux.ibm.com, jaka@...ux.ibm.com, tonylu@...ux.alibaba.com,
	guwen@...ux.alibaba.com, davem@...emloft.net, edumazet@...gle.com,
	kuba@...nel.org, pabeni@...hat.com, horms@...nel.org,
	linux-rdma@...r.kernel.org, linux-s390@...r.kernel.org,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
	skhan@...uxfoundation.org, jserv@...s.ncku.edu.tw,
	linux-kernel-mentees@...ts.linux.dev
Subject: Re: [PATCH] net/smc: Reduce size of smc_wr_tx_tasklet_fn

On 2025-03-15 14:25:16, I Hsin Cheng wrote:
>The variable "polled" in smc_wr_tx_tasklet_fn is a counter to determine
>whether the loop has been executed for the first time. Refactor the type
>of "polled" from "int" to "bool" can reduce the size of generated code
>size by 12 bytes shown with the test below
>
>$ ./scripts/bloat-o-meter vmlinux_old vmlinux_new
>add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-12 (-12)
>Function                                     old     new   delta
>smc_wr_tx_tasklet_fn                        1076    1064     -12
>Total: Before=24795091, After=24795079, chg -0.00%
>
>In some configuration, the compiler will complain this function for
>exceeding 1024 bytes for function stack, this change can at least reduce
>the size by 12 bytes within manner.
>
>Signed-off-by: I Hsin Cheng <richard120310@...il.com>

Reviewed-by: Dust Li <dust.li@...ux.alibaba.com>

Best regards,
Dust

>---
> net/smc/smc_wr.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
>diff --git a/net/smc/smc_wr.c b/net/smc/smc_wr.c
>index b04a21b8c511..3cc435ed7fde 100644
>--- a/net/smc/smc_wr.c
>+++ b/net/smc/smc_wr.c
>@@ -138,14 +138,14 @@ static void smc_wr_tx_tasklet_fn(struct tasklet_struct *t)
> 	struct smc_ib_device *dev = from_tasklet(dev, t, send_tasklet);
> 	struct ib_wc wc[SMC_WR_MAX_POLL_CQE];
> 	int i = 0, rc;
>-	int polled = 0;
>+	bool polled = false;
> 
> again:
>-	polled++;
>+	polled = !polled;
> 	do {
> 		memset(&wc, 0, sizeof(wc));
> 		rc = ib_poll_cq(dev->roce_cq_send, SMC_WR_MAX_POLL_CQE, wc);
>-		if (polled == 1) {
>+		if (polled) {
> 			ib_req_notify_cq(dev->roce_cq_send,
> 					 IB_CQ_NEXT_COMP |
> 					 IB_CQ_REPORT_MISSED_EVENTS);
>@@ -155,7 +155,7 @@ static void smc_wr_tx_tasklet_fn(struct tasklet_struct *t)
> 		for (i = 0; i < rc; i++)
> 			smc_wr_tx_process_cqe(&wc[i]);
> 	} while (rc > 0);
>-	if (polled == 1)
>+	if (polled)
> 		goto again;
> }
> 
>-- 
>2.43.0
>