Re: [2.4.17/18pre] VM and swap - it's really unusable

["M.H.VanLeeuwen" <vanl@megsinet.net>]

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Stephan von Krawczynski wrote:
> 
> On Mon, 31 Dec 2001 11:14:04 -0600
> "M.H.VanLeeuwen" <vanl@megsinet.net> wrote:
> 
> > [...]
> > vmscan patch:
> >
> > a. instead of calling swap_out as soon as max_mapped is reached, continue to
> try>    to free pages.  this reduces the number of times we hit
> try_to_free_pages() and>    swap_out().
> 
> I experimented with this some time ago, but found out it hit performance and
> (to my own surprise) did not do any good at all. Have you tried this
> stand-alone/on top of the rest to view its results?
> 
> Regards,
> Stephan

Stephan,

Here is what I've run thus far.  I'll add nfs file copy into the mix also...

System: SMP 466 Celeron 192M RAM, running KDE, xosview, and other minor apps.

Each run after clean & cache builds has 1 more setiathome client running upto a
max if 8 seti clients.  No, this isn't my normal way of running setiathome, but
each instance uses a nice chunk of memory.

Note: this is a single run for each of the columns using "make -j2 bzImage" each time.

I will try to run aa and rmap this evening and/or tomorrow.

Martin

----------------------------------------------------------------------------

                STOCK KERNEL    MH KERNEL       STOCK + SWAP    MH + SWAP
                (no swap)       (no swap)

CLEAN
BUILD   real    7m19.428s       7m19.546s       7m26.852s       7m26.256s
        user    12m53.640s      12m50.550s      12m53.740s      12m47.110s
        sys     0m47.890s       0m54.960s       0m58.810s       1m1.090s
                                                1.1M swp        0M swp

CACHE
BUILD   real    7m3.823s        7m3.520s        7m4.040s        7m4.266s
        user    12m47.710s      12m49.110s      12m47.640s      12m40.120s
        sys     0m46.660s       0m46.270s       0m47.480s       0m51.440s
                                                1.1M swp        0M swp

SETI 1
        real    9m51.652s       9m50.601s       9m53.153s       9m53.668s
        user    13m5.250s       13m4.420s       13m5.040s       13m4.470s
        sys     0m49.020s       0m50.460s       0m51.190s       0m50.580s
                                                1.1M swp        0M swp

SETI 2
        real    13m9.730s       13m7.719s       13m4.279s       13m4.768s
        user    13m16.810s      13m15.150s      13m15.950s      13m13.400s
        sys     0m50.880s       0m50.460s       0m50.930s       0m52.520s
                                                5.8M swp        1.9M swp

SETI 3
        real    15m49.331s      15m41.264s      15m40.828s      15m45.551s
        user    13m22.150s      13m21.560s      13m14.390s      13m20.790s
        sys     0m49.250s       0m49.910s       0m49.850s       0m50.910s
                                                16.2M swp       3.1M swp

SETI 4
        real    OOM KILLED      19m8.435s       19m5.584s       19m3.618s
        user    kdeinit         13m24.570s      13m24.000s      13m22.520s
        sys                     0m51.430s       0m50.320s       0m51.390s
                                                18.7M swp       8.3M swp
SETI 5
        real    NA              21m35.515s      21m48.543s      22m0.240s
        user                    13m9.680s       13m22.030s      13m28.820s
        sys                     0m49.910s       0m50.850s       0m52.270s
                                                31.7M swp       11.3M swp

SETI 6
        real    NA              24m37.167s      25m5.244s       25m13.429s
        user                    13m7.650s       13m26.590s      13m32.640s
        sys                     0m51.390s       0m51.260s       0m52.790s
                                                35.3M swp       17.1M swp

SETI 7
        real    NA              28m40.446s      28m3.612s       28m12.981s
        user                    13m16.460s      13m26.130s      13m31.520s
        sys                     0m57.940s       0m52.510s       0m53.570s
                                                38.8M swp       25.4M swp

SETI 8
        real    NA              29m31.743s      31m16.275s      32m29.534s
        user                    13m37.610s      13m27.740s      13m33.630s
        sys                     1m4.450s        0m52.100s       0m54.140s
                                                41.5M swp       49.7M swp (hmmm?)

[-- Attachment #2: vmscan.patch.2.4.17.c --]
[-- Type: application/octet-stream, Size: 1275 bytes --]

--- linux.virgin/mm/vmscan.c	Mon Dec 31 12:46:25 2001
+++ linux/mm/vmscan.c	Thu Jan  3 19:43:02 2002
@@ -394,9 +394,9 @@
 		if (PageDirty(page) && is_page_cache_freeable(page) && page->mapping) {
 			/*
 			 * It is not critical here to write it only if
-			 * the page is unmapped beause any direct writer
+			 * the page is unmapped because any direct writer
 			 * like O_DIRECT would set the PG_dirty bitflag
-			 * on the phisical page after having successfully
+			 * on the physical page after having successfully
 			 * pinned it and after the I/O to the page is finished,
 			 * so the direct writes to the page cannot get lost.
 			 */
@@ -480,11 +480,14 @@
 
 			/*
 			 * Alert! We've found too many mapped pages on the
-			 * inactive list, so we start swapping out now!
+			 * inactive list.
+			 * Move referenced pages to the active list.
 			 */
-			spin_unlock(&pagemap_lru_lock);
-			swap_out(priority, gfp_mask, classzone);
-			return nr_pages;
+			if (PageReferenced(page)) {
+				del_page_from_inactive_list(page);
+				add_page_to_active_list(page);
+			}
+			continue;
 		}
 
 		/*
@@ -521,6 +524,9 @@
 	}
 	spin_unlock(&pagemap_lru_lock);
 
+	if (max_mapped <= 0 && nr_pages > 0)
+		swap_out(priority, gfp_mask, classzone);
+
 	return nr_pages;
 }