Again... :-(
Patch included this time...
/RogerL
Roger Larsson wrote:
>
> Hi Linus,
>
> Cleaned up and corrected some bugs...
> (memory_pressure... !
> unintended reschedule removed)
>
> Sadly the performance went down - slightly.
> Latency looks even nicer. Still some spikes.
> [sync and mmap002 behaviour not corrected]
>
> /RogerL
>
> Roger Larsson wrote:
> >
> > Hi Linus,
> >
> > [patch against linux-2.4.0-test3-pre2]
> >
> > I cleaned up kswapd and moved its reschedule point.
> > Disk performance is close to the same.
> > Latencies have improved a lot (tested with Bennos latencytest)
> >
> > * sync is still problematic
> > * mmap002 (Quintinela) still gives a 212 ms latency
> > (compared to 423 ms for the unpatched...)
> > * other disk related latencies are down under 30 ms.
> > (streaming read, copy, write)
> > * the number of overruns has dropped considerably!
> > (running 4 buffers with a deadline of 23 ms)
> >
> > /RogerL
> >
> > --
> > Home page:
> > http://www.norran.net/nra02596/
> >
> > ------------------------------------------------------------------------
> > Name: patch-2.4.0-test3-pre2-vmscan.latency.2
> > patch-2.4.0-test3-pre2-vmscan.latency.2 Type: Plain Text (text/plain)
> > Encoding: 7bit
>
> --
> Home page:
> http://www.norran.net/nra02596/
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
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-- Home page: http://www.norran.net/nra02596/
diff -aurp linux-2.4.0-test3-pre2/mm/vmscan.c linux/mm/vmscan.c --- linux-2.4.0-test3-pre2/mm/vmscan.c Wed May 31 20:13:37 2000 +++ linux/mm/vmscan.c Wed Jul 5 00:52:59 2000 @@ -419,6 +419,48 @@ out: } /* + * Check if there is any memory pressure (free_pages < pages_low) + */ +static inline int memory_pressure(void) +{ + pg_data_t *pgdat = pgdat_list; + + do { + int i; + for(i = 0; i < MAX_NR_ZONES; i++) { + zone_t *zone = pgdat->node_zones+ i; + if (zone->size && + zone->free_pages < zone->pages_low) + return 1; + } + pgdat = pgdat->node_next; + } while (pgdat); + + return 0; +} + +/* + * Check if there is any memory pressure (free_pages < pages_low) + */ +static inline int keep_kswapd_awake(void) +{ + pg_data_t *pgdat = pgdat_list; + + do { + int i; + for(i = 0; i < MAX_NR_ZONES; i++) { + zone_t *zone = pgdat->node_zones+ i; + if (zone->size && + zone->zone_wake_kswapd) + return 1; + } + pgdat = pgdat->node_next; + } while (pgdat); + + return 0; +} + +/* * We need to make the locks finer granularity, but right * now we need this so that we can do page allocations * without holding the kernel lock etc. @@ -442,11 +484,28 @@ static int do_try_to_free_pages(unsigned priority = 64; do { + /* should __GFP_WAIT be checked? + * assume not - not WAITING for a free page + * let more important task execute before + * continuing (Note: kswapd does not use it). + */ + if (current->need_resched) { + schedule(); + /* time has passed - pressure too? */ + if (!memory_pressure()) + goto done; + } + while (shrink_mmap(priority, gfp_mask)) { if (!--count) goto done; } + /* not (been) low on memory - it is + * pointless to try to swap out. + */ + if (!keep_kswapd_awake()) + goto done; /* Try to get rid of some shared memory pages.. */ if (gfp_mask & __GFP_IO) { @@ -457,8 +516,18 @@ static int do_try_to_free_pages(unsigned */ count -= shrink_dcache_memory(priority, gfp_mask); count -= shrink_icache_memory(priority, gfp_mask); - if (count <= 0) - goto done; + /* + * Not currently working, see fixme in shrink_?cache_memory + * In the inner funtions there is a comment: + * "To help debugging, a zero exit status indicates + * all slabs were released." (-arca?) + * lets handle it in a primitive but working way... + * if (count <= 0) + * goto done; + */ + if (!keep_kswapd_awake()) + goto done; + while (shm_swap(priority, gfp_mask)) { if (!--count) goto done; @@ -477,7 +546,8 @@ static int do_try_to_free_pages(unsigned if (--swap_count < 0) break; - } while (--priority >= 0); + priority--; + } while (priority >= 0); /* Always end on a shrink_mmap.. */ while (shrink_mmap(0, gfp_mask)) { @@ -486,7 +556,7 @@ static int do_try_to_free_pages(unsigned } /* We return 1 if we are freed some page */ return (count != FREE_COUNT); - + done: return 1; } @@ -530,29 +600,14 @@ int kswapd(void *unused) tsk->flags |= PF_MEMALLOC; for (;;) { - pg_data_t *pgdat; - int something_to_do = 0; - - pgdat = pgdat_list; - do { - int i; - for(i = 0; i < MAX_NR_ZONES; i++) { - zone_t *zone = pgdat->node_zones+ i; - if (tsk->need_resched) - schedule(); - if (!zone->size || !zone->zone_wake_kswapd) - continue; - if (zone->free_pages < zone->pages_low) - something_to_do = 1; - do_try_to_free_pages(GFP_KSWAPD); - } - pgdat = pgdat->node_next; - } while (pgdat); - - if (!something_to_do) { - tsk->state = TASK_INTERRUPTIBLE; - interruptible_sleep_on(&kswapd_wait); + if (!keep_kswapd_awake()) { + /* wake up regulary to do an early attempt too free + * pages - pages will not actually be freed. + */ + interruptible_sleep_on_timeout(&kswapd_wait, HZ); } + + do_try_to_free_pages(GFP_KSWAPD); } } @@ -580,6 +635,12 @@ int try_to_free_pages(unsigned int gfp_m retval = do_try_to_free_pages(gfp_mask); current->flags &= ~PF_MEMALLOC; } + else { + /* make sure kswapd runs */ + if (waitqueue_active(&kswapd_wait)) + wake_up_interruptible(&kswapd_wait); + } + return retval; }
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This archive was generated by hypermail 2b29 : Fri Jul 07 2000 - 21:00:17 EST