linux-kernel - [PATCH AUTOSEL 5.4 12/37] cifs: ask for more credit on async read/write code paths

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Message-Id: <20210317005802.725825-12-sashal@kernel.org>
Date:   Tue, 16 Mar 2021 20:57:37 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Aurelien Aptel <aaptel@...e.com>,
        Shyam Prasad N <sprasad@...rosoft.com>,
        Steve French <stfrench@...rosoft.com>,
        Sasha Levin <sashal@...nel.org>, linux-cifs@...r.kernel.org,
        samba-technical@...ts.samba.org
Subject: [PATCH AUTOSEL 5.4 12/37] cifs: ask for more credit on async read/write code paths

From: Aurelien Aptel <aaptel@...e.com>

[ Upstream commit 88fd98a2306755b965e4f4567f84e73db3b6738c ]

When doing a large read or write workload we only
very gradually increase the number of credits
which can cause problems with parallelizing large i/o
(I/O ramps up more slowly than it should for large
read/write workloads) especially with multichannel
when the number of credits on the secondary channels
starts out low (e.g. less than about 130) or when
recovering after server throttled back the number
of credit.

Signed-off-by: Aurelien Aptel <aaptel@...e.com>
Reviewed-by: Shyam Prasad N <sprasad@...rosoft.com>
Signed-off-by: Steve French <stfrench@...rosoft.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/cifs/smb2pdu.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index 7adecfd0c1e9..81d9c4ea0e8f 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -3743,8 +3743,7 @@ smb2_async_readv(struct cifs_readdata *rdata)
 	if (rdata->credits.value > 0) {
 		shdr->CreditCharge = cpu_to_le16(DIV_ROUND_UP(rdata->bytes,
 						SMB2_MAX_BUFFER_SIZE));
-		shdr->CreditRequest =
-			cpu_to_le16(le16_to_cpu(shdr->CreditCharge) + 1);
+		shdr->CreditRequest = cpu_to_le16(le16_to_cpu(shdr->CreditCharge) + 8);
 
 		rc = adjust_credits(server, &rdata->credits, rdata->bytes);
 		if (rc)
@@ -4038,8 +4037,7 @@ smb2_async_writev(struct cifs_writedata *wdata,
 	if (wdata->credits.value > 0) {
 		shdr->CreditCharge = cpu_to_le16(DIV_ROUND_UP(wdata->bytes,
 						    SMB2_MAX_BUFFER_SIZE));
-		shdr->CreditRequest =
-			cpu_to_le16(le16_to_cpu(shdr->CreditCharge) + 1);
+		shdr->CreditRequest = cpu_to_le16(le16_to_cpu(shdr->CreditCharge) + 8);
 
 		rc = adjust_credits(server, &wdata->credits, wdata->bytes);
 		if (rc)
-- 
2.30.1