That syscall trace is useful. It turns out that the emulation for lseek(2) still resides in the brand library, rather than the kernel module. While it may not represent the entire differential in performance, it's a place to start. I've filed OS-5583 to that end.
On 9 August 2016 at 03:24, Ian Collins <[email protected]> wrote: > On 08/ 9/16 01:46 AM, Robert Mustacchi wrote: >> >> On 8/7/16 2:40 , Ian Collins wrote: >>> >>> >>> One thing that did surprise me testing on his box is the software builds >>> significantly faster in a KVM than in an LX zone. The difference is >>> most noticeable with linking where one target takes well over twice as >>> long in the zone. >>> >>> KVM: >>> >>> $ time ninja bin/Posix_Debug/Tests >>> [1/1] LINK bin/Posix_Debug/Tests >>> real 1m3.693s >>> user 0m55.470s >>> sys 0m7.772s >>> >>> Zone: >>> >>> $ time ninja bin/Posix_Debug/Tests >>> [1/1] LINK bin/Posix_Debug/Tests >>> real 2m45.004s >>> user 1m35.427s >>> sys 1m7.567s >>> >> Well, I'd probably start with two angles. The first is where do the >> microstates say you're spending your time during the link. Let's make >> sure there's no LAT on the scene. Otherwise, I might do something like >> profile where we're spending our SYS time and try and break that down >> further. Maybe just running the individual link command with ptime -m >> would be a good start. > > > PID USERNAME USR SYS TRP TFL DFL LCK SLP LAT VCX ICX SCL SIG > PROCESS/LWPID > 30176 1005 84 16 0.0 0.0 0.0 0.0 0.0 0.0 0 452 .1M 0 > x86_64-linux/1 > > Lots of system calls. > > Using dtrace for a couple of seconds: > > # dtrace -n 'lx-syscall:::entry { @num[pid,execname] = count(); }' > dtrace: description 'lx-syscall:::entry ' matched 676 probes > ^C > > 30090 x86_64-linux-gnu 4019849 > > Over the run time of the link (top few): > > # dtrace -n 'lx-syscall:::entry { @num[probefunc] = count(); }' > dtrace: description 'lx-syscall:::entry ' matched 676 probes > ^C > mmap 87 > stat 334 > close 1299 > open 1407 > fstat 1834 > fcntl 2414 > brk 15685 > write 627589 > read 3185104 > lseek 13520417 > > Which is what I'd expect for a link that consumes 3.5GB of RAM... > > -- > Ian. > ------------------------------------------- smartos-discuss Archives: https://www.listbox.com/member/archive/184463/=now RSS Feed: https://www.listbox.com/member/archive/rss/184463/25769125-55cfbc00 Modify Your Subscription: https://www.listbox.com/member/?member_id=25769125&id_secret=25769125-7688e9fb Powered by Listbox: http://www.listbox.com
