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nfsd: fix performance-limiting session calculation

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commit c54f24e338 upstream.

We're unintentionally limiting the number of slots per nfsv4.1 session
to 10.  Often more than 10 simultaneous RPCs are needed for the best
performance.

This calculation was meant to prevent any one client from using up more
than a third of the limit we set for total memory use across all clients
and sessions.  Instead, it's limiting the client to a third of the
maximum for a single session.

Fix this.

Reported-by: Chris Tracy <ctracy@engr.scu.edu>
Cc: stable@vger.kernel.org
Fixes: de766e5704 "nfsd: give out fewer session slots as limit approaches"
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
J. Bruce Fields 2019-02-21 10:47:00 -05:00 committed by Greg Kroah-Hartman
parent 2c648caf63
commit 10a68cdf10
1 changed files with 4 additions and 4 deletions
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8
fs/nfsd/nfs4state.c
View file

@ -1514,16 +1514,16 @@ static u32 nfsd4_get_drc_mem(struct nfsd4_channel_attrs *ca)
{
u32 slotsize = slot_bytes(ca);
u32 num = ca->maxreqs;
int avail;
unsigned long avail, total_avail;
spin_lock(&nfsd_drc_lock);
avail = min((unsigned long)NFSD_MAX_MEM_PER_SESSION,
nfsd_drc_max_mem - nfsd_drc_mem_used);
total_avail = nfsd_drc_max_mem - nfsd_drc_mem_used;
avail = min((unsigned long)NFSD_MAX_MEM_PER_SESSION, total_avail);
/*
* 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);
avail = clamp_t(int, avail, slotsize, total_avail/3);
num = min_t(int, num, avail / slotsize);
nfsd_drc_mem_used += num * slotsize;
spin_unlock(&nfsd_drc_lock);