[email protected] a écrit : > The system is unicore? Nope.
i7-4770, four cores, eight threads.
> Isn't it simply almost thrashing? Too many
> processes (that may even have threads) hence too many context switches
> for an unsufficient number of cores?
I don't think. This server acts as :
- tftpd boot server ;
- NIS server ;
- NFS server (for mainly two active clients, and three or four idle
clients). On client side, disks are mounted with async option.
If I restart nfsd with only 16 threads, of course, load average on
server doesn't rise until 100, but there is a lot of "server not
responding" messages on client sides. For me, bottleneck is between nfs
server and disk subsystem.
To be honnest, there are a lot of tiny services (local DNS, MX2 with a
very little traffic. With not special NFS transations, mean load average
remains between 0 and 1 :
load averages: 0.32, 0.60, 0.52; up 16+02:46:28
11:28:25
85 processes: 84 sleeping, 1 on CPU
CPU0 states: 0.5% user, 0.0% nice, 0.0% system, 0.5% interrupt,
99.0% idle
CPU1 states: 0.0% user, 0.0% nice, 0.5% system, 0.0% interrupt,
99.5% idle
CPU2 states: 0.0% user, 0.0% nice, 1.0% system, 0.2% interrupt,
98.8% idle
CPU3 states: 0.0% user, 0.0% nice, 0.0% system, 0.0% interrupt,
100% idle
CPU4 states: 0.0% user, 0.0% nice, 0.0% system, 0.0% interrupt,
100% idle
CPU5 states: 0.0% user, 0.0% nice, 0.0% system, 0.0% interrupt,
100% idle
CPU6 states: 0.0% user, 0.0% nice, 0.0% system, 0.0% interrupt,
100% idle
CPU7 states: 0.0% user, 0.0% nice, 0.0% system, 0.0% interrupt,
100% idle
Memory: 7079M Act, 3881M Inact, 49M Wired, 146M Exec, 8854M File, 865M Free
Swap: 16G Total, 16G Free / Pools: 3742M Used / Network: 855K In, 4230K Out
Locally, on raid5 volume :
legendre:[~] > dd if=/dev/zero of=test.dd bs=100m count=10
10+0 records in
10+0 records out
1048576000 bytes transferred in 4.246 secs (246956194 bytes/sec)
On Raid1 :
legendre# dd if=/dev/zero of=test.dd bs=100m count=10
10+0 records in
10+0 records out
1048576000 bytes transferred in 3.291 secs (318619264 bytes/sec)
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