Re: [lockup] Re: objrmap-core-1 (rmap removal for file mappings to avoid 4:4 in <=16G machines)

Marcelo Tosatti
2004-03-16T08:35:15Z

On Mon, 15 Mar 2004, Andrea Arcangeli wrote:

> On Mon, Mar 15, 2004 at 04:47:48PM -0300, Marcelo Tosatti wrote:
> >
> >
> > On Tue, 9 Mar 2004, Andrea Arcangeli wrote:
> >
> > > this doesn't lockup for me (in 2.6 + objrmap), but the machine is not
> > > responsive, while pushing 1G into swap. Here a trace in the middle of the
> > > swapping while pressing C^c on your program doesn't respond for half a minute.
> > >
> > > Mind to leave it running a bit longer before claiming a lockup?
> > >
> > > 1 206 615472 4032 84 879332 11248 16808 16324 16808 2618 20311 0 43 0 57
> > > 1 204 641740 1756 96 878476 2852 16980 4928 16980 5066 60228 0 35 1 64
> > > 1 205 650936 2508 100 875604 2248 9928 3772 9928 1364 21052 0 34 2 64
> > > 2 204 658212 2656 104 876904 3564 12052 4988 12052 2074 19647 0 32 1 67
> > > 1 204 674260 1628 104 878528 3236 12924 5608 12928 2062 27114 0 47 0 53
> > > 1 204 678248 1988 96 879004 3540 4664 4360 4664 1988 20728 0 31 0 69
> > > 1 203 683748 4024 96 878132 2844 5036 3724 5036 1513 18173 0 38 0 61
> > > 0 206 687312 1732 112 879056 3396 4260 4424 4272 1704 13222 0 32 0 68
> > > 1 204 690164 1936 116 880364 2844 3400 3496 3404 1422 18214 0 35 0 64
> > > 0 205 696572 4348 112 877676 2956 6620 3788 6620 1281 11544 0 37 1 62
> > > 0 204 699244 4168 108 878272 3140 3528 3892 3528 1467 11464 0 28 0 72
> > > 1 206 704296 1820 112 878604 2576 4980 3592 4980 1386 11710 0 26 0 74
> > > 1 205 710452 1972 104 876760 2256 6684 3092 6684 1308 20947 0 34 1 66
> > > 2 203 714512 1632 108 877564 2332 4876 3068 4876 1295 9792 0 20 0 80
> > > 0 204 719804 3720 112 878128 2536 6352 3100 6368 1441 20714 0 39 0 61
> > > 124 200 724708 1636 100 879548 3376 5308 3912 5308 1516 20732 0 38 0 62
> > > procs -----------memory---------- ---swap-- -----io---- --system-- ----cpu----
> > > r b swpd free buff cache si so bi bo in cs us sy id wa
> > > 1 204 730908 4344 100 877528 2592 6356 3672 6356 1819 15894 0 35 0 65
> > > 0 204 733556 3836 104 878256 2312 3132 3508 3132 1294 10905 0 33 0 67
> > > 0 205 736380 3388 100 877376 3084 3364 3832 3364 1322 11550 0 30 0 70
> > > 1 206 747016 2032 100 877760 2780 13144 4272 13144 1564 17486 0 37 0 63
> > > 1 205 756664 2192 96 878004 1704 7704 2116 7704 1341 20056 0 32 0 67
> > > 9 203 759084 3200 92 878516 2748 3168 3676 3168 1330 18252 0 45 0 54
> > > 0 205 761752 3928 96 877208 2604 2984 3284 2984 1330 10395 0 35 0 65
> > >
> > > most of the time is spent in "wa", though it's a 4-way, so it means at least
> > > two cpus are spinning. I'm pushing the box hard into swap. 2.6 swap extremely
> > > slow w/ or w/o objrmap, not much difference really w/o or w/o your exploit.
> >
> > Andrea,
> >
> > I did some swapping tests with 2.6 and found out that it was really slow,
> > too. Very unresponsive under heavy swapping.
> >
> > -mm fixed things for me. Not sure parts of it do the trick, though.
> >
> > Can you be more specific on the "slow swap" comment you made ?
>
> well, it's just the swapin/swapout rate being too slow as you noticed. I
> didn't benchmark -mm in swap workloads, so it may very well be fixed in
> -mm with Nick's patches. At this point in time I've more serious
> troubles than the swap speed, and -mm can't help me with those troubles
> (4:4 is a last resort I can take from the -mm tree, but I'm trying as
> much as I can to avoid forcing people to 4:4 on the <=16G machines that
> have huge margins with 3:1 and 2.4-aa, 32G are used to work fine too
> with 3:1 on 2.4-aa, infact I'm trying to avoid 4:4 even on the 64G
> machines).

What are the problems you are facing ? Yes, I could read the previous
posts, etc. but a nice resume is always good, for me, for others, and for
you :)

Yes, 4:4 tlb flushing is, hum, not very cool.