Comment 584 for bug 620074

Good day, anybody!

I found фт optimal options against this and like this bug
Anybody please try a following options.

I found that my kernels 2.6* and 3.2.* and 3.3.* versions of my server has periodical freezings 4-15 secs. I found that this occur in writeback time (flushing to disk) in time when 30sec expires for expired dirty pages occur. I tried many variants of dirty_* options and found optimal these:

I can suggest two veriants
Here 1st and 2nd variants
The second variant commented
Only uncommment second lines and nothing

#######################################
# every 3 sec look up for dirty status
# It for smooting writebacking, may be 100 will be better
echo 300 > /proc/sys/vm/dirty_writeback_centisecs

# Only 100Kb data of dirty pages and writeback...
# It very important option :)
echo 102400 > /proc/sys/vm/dirty_background_bytes

# second variant - uncomment it - but you will have frozens but rarely
# echo 225280000 > /proc/sys/vm/dirty_background_bytes

# my a frozens happen at time of expiring of dirty pages (default 30 sec)
# i increased it (it doesn't mean for 1st variant - it will never happen)
echo 864000 > /proc/sys/vm/dirty_expire_centisecs

# I increased limit for non background writebacking (it never happens i think)
echo 10 > /proc/sys/vm/dirty_ratio

#######################################

I like 1st variant - my system now works smooth
I found that freezings occurs when dirty pages are written to disk.
You can see it by this:

watch -n1 grep -A 1 dirty /proc/vmstat

New kernel features from 3.2.* version (writeback throttling) will not help to me. Now i tested kernel 3.3.2-6 of FC16 and it have a troubles too. But these settings work for me!

I don't have any time for detailed description
But if you will test it and it will help i will ready to discus for it
Sorry for my English :)

Bye!
Perlover