Messages in this thread Patch in this message | | | Date | Fri, 23 Feb 2007 21:04:03 +0900 | From | Tomoki Sekiyama <> | Subject | [RFC][PATCH 3/3] VM throttling: Break on no more Dirty pages |
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This modifies balance_dirty_pages() not to block the caller when the amount of Dirty+Writeback is less than `vm.dirty_limit_ratio' percent of the total memory.
throttle_vm_writeout() is also changed to calculate the threshold from the new limit provided by modified get_dirty_limits().
Signed-off-by: Tomoki Sekiyama <tomoki.sekiyama.qu@hitachi.com> Signed-off-by: Yuji Kakutani <yuji.kakutani.uw@hitachi.com> --- mm/page-writeback.c | 28 ++++++++++++++++------------ 1 file changed, 16 insertions(+), 12 deletions(-)
Index: linux-2.6.20-mm2-bdp/mm/page-writeback.c =================================================================== --- linux-2.6.20-mm2-bdp.orig/mm/page-writeback.c +++ linux-2.6.20-mm2-bdp/mm/page-writeback.c @@ -219,12 +219,15 @@ get_dirty_limits(long *pbackground, long * balance_dirty_pages() must be called by processes which are generating dirty * data. It looks at the number of dirty pages in the machine and will force * the caller to perform writeback if the system is over `vm_dirty_ratio'. + * If the caller couldn't writeback `write_chunk' pages and we're over + * `dirty_limit_ratio', the caller will be blocked. * If we're over `background_thresh' then pdflush is woken to perform some * writeout. */ static void balance_dirty_pages(struct address_space *mapping) { long nr_reclaimable; + long nr_dirty; long background_thresh; long dirty_thresh; long dirty_limit; @@ -246,9 +249,9 @@ static void balance_dirty_pages(struct a &dirty_limit, mapping); nr_reclaimable = global_page_state(NR_FILE_DIRTY) + global_page_state(NR_UNSTABLE_NFS); - if (nr_reclaimable + global_page_state(NR_WRITEBACK) <= - dirty_thresh) - break; + nr_dirty = nr_reclaimable + global_page_state(NR_WRITEBACK); + if (nr_dirty <= dirty_thresh) + break;
if (!dirty_exceeded) dirty_exceeded = 1; @@ -265,20 +268,21 @@ static void balance_dirty_pages(struct a &dirty_limit, mapping); nr_reclaimable = global_page_state(NR_FILE_DIRTY) + global_page_state(NR_UNSTABLE_NFS); - if (nr_reclaimable + - global_page_state(NR_WRITEBACK) - <= dirty_thresh) - break; + nr_dirty = nr_reclaimable + + global_page_state(NR_WRITEBACK); + if (nr_dirty <= dirty_thresh) + break; pages_written += write_chunk - wbc.nr_to_write; if (pages_written >= write_chunk) break; /* We've done our duty */ + if (nr_dirty <= dirty_limit) + break; /* no more dirty pages on bdi */ } congestion_wait(WRITE, HZ/10); }
- if (nr_reclaimable + global_page_state(NR_WRITEBACK) - <= dirty_thresh && dirty_exceeded) - dirty_exceeded = 0; + if (nr_dirty <= dirty_thresh && dirty_exceeded) + dirty_exceeded = 0;
if (writeback_in_progress(bdi)) return; /* pdflush is already working this queue */ @@ -362,10 +366,10 @@ void throttle_vm_writeout(void) * Boost the allowable dirty threshold a bit for page * allocators so they don't get DoS'ed by heavy writers */ - dirty_thresh += dirty_thresh / 10; /* wheeee... */ + dirty_limit += dirty_limit / 10; /* wheeee... */
if (global_page_state(NR_UNSTABLE_NFS) + - global_page_state(NR_WRITEBACK) <= dirty_thresh) + global_page_state(NR_WRITEBACK) <= dirty_limit) break; congestion_wait(WRITE, HZ/10); } - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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