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From: "J. Bruce Fields" <bfields@redhat.com>
To: linux-nfs@vger.kernel.org
Cc: "J. Bruce Fields" <bfields@redhat.com>
Subject: [PATCH 2/2] nfsd: give out fewer session slots as limit approaches
Date: Mon, 25 Sep 2017 09:21:44 -0400
Message-ID: <1506345704-9486-3-git-send-email-bfields@redhat.com> (raw)
In-Reply-To: <1506345704-9486-1-git-send-email-bfields@redhat.com>

From: "J. Bruce Fields" <bfields@redhat.com>

Instead of granting client's full requests until we hit our DRC size
limit and then failing CREATE_SESSIONs (and hence mounts) completely,
start granting clients smaller slot tables as we approach the limit.

The factor chosen here is pretty much arbitrary.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>
---
 fs/nfsd/nfs4state.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 28e5bded6a4b..2fe930e92545 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -1472,6 +1472,11 @@ static u32 nfsd4_get_drc_mem(struct nfsd4_channel_attrs *ca)
 	spin_lock(&nfsd_drc_lock);
 	avail = min((unsigned long)NFSD_MAX_MEM_PER_SESSION,
 		    nfsd_drc_max_mem - nfsd_drc_mem_used);
+	/*
+	 * Never use more than a third of the remaining memory,
+	 * unless it's the only way to give this client a slot:
+	 */
+	avail = clamp_t(int, avail, slotsize, avail/3);
 	num = min_t(int, num, avail / slotsize);
 	nfsd_drc_mem_used += num * slotsize;
 	spin_unlock(&nfsd_drc_lock);
-- 
2.13.5


  parent reply index

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-09-25 13:21 [PATCH 0/2] tweak knfsd session slot table sizing J. Bruce Fields
2017-09-25 13:21 ` [PATCH 1/2] nfsd: increase DRC cache limit J. Bruce Fields
2017-09-25 13:21 ` J. Bruce Fields [this message]
2019-09-19  1:08   ` [PATCH 2/2] nfsd: give out fewer session slots as limit approaches NeilBrown
2019-09-19 16:22     ` J. Bruce Fields
2019-09-19 17:17       ` J. Bruce Fields
2019-09-19 18:41         ` bfields
2019-09-20  6:15           ` [PATCH 1/2] nfsd: handle drc over-allocation gracefully NeilBrown
2019-09-20  6:33             ` [PATCH 1/2 - vers2] " NeilBrown
2019-09-20  6:36               ` [PATCH - 2/2] nfsd: degraded slot-count more gracefully as allocation nears exhaustion NeilBrown
2019-09-20 16:28               ` [PATCH 1/2 - vers2] nfsd: handle drc over-allocation gracefully J. Bruce Fields

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