[Bug 678466] New: Swap over NFS reserves too much memory on openSUSE-11.4

newer
[Bug 712012] New: Xen package list...

bugzilla_noreply＠novell.com

10 Mar 2011 10 Mar '11

10:49

https://bugzilla.novell.com/show_bug.cgi?id=678466 https://bugzilla.novell.com/show_bug.cgi?id=678466#c0 Summary: Swap over NFS reserves too much memory on openSUSE-11.4 Classification: openSUSE Product: openSUSE 11.4 Version: RC 2 Platform: All OS/Version: SuSE Other Status: NEW Severity: Normal Priority: P5 - None Component: Kernel AssignedTo: mgorman@novell.com ReportedBy: mgorman@novell.com QAContact: qa@suse.de CC: sjayaraman@novell.com Found By: Development Blocker: No Swap over NFS implements a memory reservation scheme to guarantee that allocations can succeed under low memory conditions when pages need to be cleaned. These reservations are extremely high. On a 2G machine, 454M of memory is reserved which far exceeds what should be necessary. This has not been verified on SLES but a glance at the patches implies the same problem exists there. -- Configure bugmail: https://bugzilla.novell.com/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are on the CC list for the bug.

Show replies by date

bugzilla_noreply＠novell.com

10 Mar 10 Mar

11:03

New subject: [Bug 678466] Swap over NFS reserves too much memory on openSUSE-11.4

https://bugzilla.novell.com/show_bug.cgi?id=678466 https://bugzilla.novell.com/show_bug.cgi?id=678466#c1 --- Comment #1 from Suresh Jayaraman 2011-03-10 11:03:49 UTC --- Ah, looks like a known but open issue https://bugzilla.novell.com/show_bug.cgi?id=661558 Computing reserves based on our assumption about the traffic flow in the form of ipv4 route max_size seems not a well thought out idea. (/proc/sys/net/ipv4/route/max_size) max_size * sizeof(ip_dst_cache) could sometimes be quite expensive It appears to me that the idea of making the max size of the routing cache dependent on size of the physical RAM is not so well thought of. A workaround is to reduce the 'route/max_size' number which should reduce the memory reservation. NeilBrown wondered whether swap-over-NFS should automatically tune it down when it is enabled. -- Configure bugmail: https://bugzilla.novell.com/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are on the CC list for the bug.

bugzilla_noreply＠novell.com

11:20

New subject: [Bug 678466] Swap over NFS reserves too much memory on openSUSE-11.4

https://bugzilla.novell.com/show_bug.cgi?id=678466 https://bugzilla.novell.com/show_bug.cgi?id=678466#c2 --- Comment #2 from Mel Gorman 2011-03-10 11:20:41 UTC --- (In reply to comment #1)

...

Ah, looks like a known but open issue https://bugzilla.novell.com/show_bug.cgi?id=661558

Whoops, my bad. This does look like the same issue all right.

...

Computing reserves based on our assumption about the traffic flow in the form of ipv4 route max_size seems not a well thought out idea. (/proc/sys/net/ipv4/route/max_size)

max_size * sizeof(ip_dst_cache) could sometimes be quite expensive

It appears to me that the idea of making the max size of the routing cache dependent on size of the physical RAM is not so well thought of.

A workaround is to reduce the 'route/max_size' number which should reduce the memory reservation.

I believe the real fix is in mm/reserve.c. There is confusion in there whether it is dealing with pages or bytes and sometimes it receives a reservation request in pages and then multiplies it by pages again. I have tested patches that should fix the problem and am in the process for converting them to a format suitable for the kernel repository. -- Configure bugmail: https://bugzilla.novell.com/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are on the CC list for the bug.

bugzilla_noreply＠novell.com

11:25

New subject: [Bug 678466] Swap over NFS reserves too much memory on openSUSE-11.4

https://bugzilla.novell.com/show_bug.cgi?id=678466 https://bugzilla.novell.com/show_bug.cgi?id=678466#c3 --- Comment #3 from Suresh Jayaraman 2011-03-10 11:25:00 UTC --- (In reply to comment #2)

...

(In reply to comment #1)

...
Ah, looks like a known but open issue https://bugzilla.novell.com/show_bug.cgi?id=661558

Whoops, my bad. This does look like the same issue all right.

No problem. I'll just mark that one as a duplicate.

...

...
Computing reserves based on our assumption about the traffic flow in the form of ipv4 route max_size seems not a well thought out idea. (/proc/sys/net/ipv4/route/max_size)

max_size * sizeof(ip_dst_cache) could sometimes be quite expensive

It appears to me that the idea of making the max size of the routing cache dependent on size of the physical RAM is not so well thought of.

A workaround is to reduce the 'route/max_size' number which should reduce the memory reservation.

I believe the real fix is in mm/reserve.c. There is confusion in there whether it is dealing with pages or bytes and sometimes it receives a reservation request in pages and then multiplies it by pages again. I have tested patches that should fix the problem and am in the process for converting them to a format suitable for the kernel repository.

Cool. We would need the fix for other repos too for e.g. SLES11 SP1 and SLE11 (if not openSUSE-11.3 -- Configure bugmail: https://bugzilla.novell.com/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are on the CC list for the bug.