* [patch 0/4] Adaptive readahead patchset V14 updates @ 2006-05-30 8:40 ` Wu Fengguang 0 siblings, 0 replies; 4+ messages in thread From: Wu Fengguang @ 2006-05-30 8:40 UTC (permalink / raw) To: Andrew Morton; +Cc: linux-kernel, Wu Fengguang Andrew, These are some fixes/updates for the adaptive readahead V14. - apply stream_shift size limits to contexta method - *remain in query_page_cache_segment() is over counted by 1, fix it - add use case comment for backward prefetching Please apply, thanks. Wu ^ permalink raw reply [flat|nested] 4+ messages in thread
* [patch 0/4] Adaptive readahead patchset V14 updates @ 2006-05-30 8:40 ` Wu Fengguang 0 siblings, 0 replies; 4+ messages in thread From: Wu Fengguang @ 2006-05-30 8:40 UTC (permalink / raw) To: Andrew Morton; +Cc: linux-kernel, Wu Fengguang Andrew, These are some fixes/updates for the adaptive readahead V14. - apply stream_shift size limits to contexta method - *remain in query_page_cache_segment() is over counted by 1, fix it - add use case comment for backward prefetching Please apply, thanks. Wu ^ permalink raw reply [flat|nested] 4+ messages in thread
* [patch 1/4] readahead: state based method - stand-alone size limit code @ 2006-05-30 8:40 ` Wu Fengguang 0 siblings, 0 replies; 4+ messages in thread From: Wu Fengguang @ 2006-05-30 8:40 UTC (permalink / raw) To: Andrew Morton; +Cc: linux-kernel, Wu Fengguang [-- Attachment #1: readahead-method-stateful-fix-size-limit-sep.patch --] [-- Type: text/plain, Size: 2594 bytes --] Separate out the readahead/lookahead sizes limiting code, and put them to stand-alone limit_rala() function. Signed-off-by: Wu Fengguang <wfg@mail.ustc.edu.cn> --- --- linux-2.6.17-rc4-mm3.orig/mm/readahead.c +++ linux-2.6.17-rc4-mm3/mm/readahead.c @@ -1009,10 +1009,8 @@ static int ra_dispatch(struct file_ra_st * - @la_size stores the look-ahead size of previous request. */ static int adjust_rala(unsigned long ra_max, - unsigned long *ra_size, unsigned long *la_size) + unsigned long *ra_size, unsigned long *la_size) { - unsigned long stream_shift = *la_size; - /* * Substract the old look-ahead to get real safe size for the next * read-ahead request. @@ -1029,8 +1027,16 @@ static int adjust_rala(unsigned long ra_ */ *la_size = *ra_size / LOOKAHEAD_RATIO; + return 1; +} + +static void limit_rala(unsigned long ra_max, unsigned long la_old, + unsigned long *ra_size, unsigned long *la_size) +{ + unsigned long stream_shift; + /* - * Apply upper limits. + * Apply basic upper limits. */ if (*ra_size > ra_max) *ra_size = ra_max; @@ -1041,11 +1047,9 @@ static int adjust_rala(unsigned long ra_ * Make sure stream_shift is not too small. * (So that the next global_shift will not be too small.) */ - stream_shift += (*ra_size - *la_size); + stream_shift = la_old + (*ra_size - *la_size); if (stream_shift < *ra_size / 4) *la_size -= (*ra_size / 4 - stream_shift); - - return 1; } /* @@ -1117,13 +1121,13 @@ state_based_readahead(struct address_spa struct page *page, pgoff_t index, unsigned long req_size, unsigned long ra_max) { - unsigned long ra_old; - unsigned long ra_size; - unsigned long la_size; + unsigned long ra_old, ra_size; + unsigned long la_old, la_size; unsigned long remain_space; unsigned long growth_limit; - la_size = ra->readahead_index - index; + la_old = la_size = ra->readahead_index - index; + ra_old = ra_readahead_size(ra); ra_size = compute_thrashing_threshold(ra, &remain_space); if (page && remain_space <= la_size && la_size > 1) { @@ -1131,7 +1135,6 @@ state_based_readahead(struct address_spa return 0; } - ra_old = ra_readahead_size(ra); growth_limit = req_size; growth_limit += ra_max / 16; growth_limit += (2 + readahead_ratio / 64) * ra_old; @@ -1141,6 +1144,8 @@ state_based_readahead(struct address_spa if (!adjust_rala(growth_limit, &ra_size, &la_size)) return 0; + limit_rala(growth_limit, la_old, &ra_size, &la_size); + ra_set_class(ra, RA_CLASS_STATE); ra_set_index(ra, index, ra->readahead_index); ra_set_size(ra, ra_size, la_size); -- ^ permalink raw reply [flat|nested] 4+ messages in thread
* [patch 1/4] readahead: state based method - stand-alone size limit code @ 2006-05-30 8:40 ` Wu Fengguang 0 siblings, 0 replies; 4+ messages in thread From: Wu Fengguang @ 2006-05-30 8:40 UTC (permalink / raw) To: Andrew Morton; +Cc: linux-kernel, Wu Fengguang [-- Attachment #1: readahead-method-stateful-fix-size-limit-sep.patch --] [-- Type: text/plain, Size: 2594 bytes --] Separate out the readahead/lookahead sizes limiting code, and put them to stand-alone limit_rala() function. Signed-off-by: Wu Fengguang <wfg@mail.ustc.edu.cn> --- --- linux-2.6.17-rc4-mm3.orig/mm/readahead.c +++ linux-2.6.17-rc4-mm3/mm/readahead.c @@ -1009,10 +1009,8 @@ static int ra_dispatch(struct file_ra_st * - @la_size stores the look-ahead size of previous request. */ static int adjust_rala(unsigned long ra_max, - unsigned long *ra_size, unsigned long *la_size) + unsigned long *ra_size, unsigned long *la_size) { - unsigned long stream_shift = *la_size; - /* * Substract the old look-ahead to get real safe size for the next * read-ahead request. @@ -1029,8 +1027,16 @@ static int adjust_rala(unsigned long ra_ */ *la_size = *ra_size / LOOKAHEAD_RATIO; + return 1; +} + +static void limit_rala(unsigned long ra_max, unsigned long la_old, + unsigned long *ra_size, unsigned long *la_size) +{ + unsigned long stream_shift; + /* - * Apply upper limits. + * Apply basic upper limits. */ if (*ra_size > ra_max) *ra_size = ra_max; @@ -1041,11 +1047,9 @@ static int adjust_rala(unsigned long ra_ * Make sure stream_shift is not too small. * (So that the next global_shift will not be too small.) */ - stream_shift += (*ra_size - *la_size); + stream_shift = la_old + (*ra_size - *la_size); if (stream_shift < *ra_size / 4) *la_size -= (*ra_size / 4 - stream_shift); - - return 1; } /* @@ -1117,13 +1121,13 @@ state_based_readahead(struct address_spa struct page *page, pgoff_t index, unsigned long req_size, unsigned long ra_max) { - unsigned long ra_old; - unsigned long ra_size; - unsigned long la_size; + unsigned long ra_old, ra_size; + unsigned long la_old, la_size; unsigned long remain_space; unsigned long growth_limit; - la_size = ra->readahead_index - index; + la_old = la_size = ra->readahead_index - index; + ra_old = ra_readahead_size(ra); ra_size = compute_thrashing_threshold(ra, &remain_space); if (page && remain_space <= la_size && la_size > 1) { @@ -1131,7 +1135,6 @@ state_based_readahead(struct address_spa return 0; } - ra_old = ra_readahead_size(ra); growth_limit = req_size; growth_limit += ra_max / 16; growth_limit += (2 + readahead_ratio / 64) * ra_old; @@ -1141,6 +1144,8 @@ state_based_readahead(struct address_spa if (!adjust_rala(growth_limit, &ra_size, &la_size)) return 0; + limit_rala(growth_limit, la_old, &ra_size, &la_size); + ra_set_class(ra, RA_CLASS_STATE); ra_set_index(ra, index, ra->readahead_index); ra_set_size(ra, ra_size, la_size); -- ^ permalink raw reply [flat|nested] 4+ messages in thread
* [patch 3/4] readahead: context based method - fix *remain counting @ 2006-05-30 8:40 ` Wu Fengguang 0 siblings, 0 replies; 4+ messages in thread From: Wu Fengguang @ 2006-05-30 8:40 UTC (permalink / raw) To: Andrew Morton; +Cc: linux-kernel, Wu Fengguang [-- Attachment #1: readahead-method-context-fix-remain.patch --] [-- Type: text/plain, Size: 514 bytes --] *remain in query_page_cache_segment() is over counted by 1, fix it. Signed-off-by: Wu Fengguang <wfg@mail.ustc.edu.cn> --- --- linux-2.6.17-rc4-mm3.orig/mm/readahead.c +++ linux-2.6.17-rc4-mm3/mm/readahead.c @@ -1334,7 +1334,7 @@ static unsigned long query_page_cache_se index = radix_tree_scan_hole_backward(&mapping->page_tree, offset - 1, ra_max); - *remain = offset - index; + *remain = (offset - 1) - index; if (offset == ra->readahead_index && ra_cache_hit_ok(ra)) count = *remain; -- ^ permalink raw reply [flat|nested] 4+ messages in thread
* [patch 3/4] readahead: context based method - fix *remain counting @ 2006-05-30 8:40 ` Wu Fengguang 0 siblings, 0 replies; 4+ messages in thread From: Wu Fengguang @ 2006-05-30 8:40 UTC (permalink / raw) To: Andrew Morton; +Cc: linux-kernel, Wu Fengguang [-- Attachment #1: readahead-method-context-fix-remain.patch --] [-- Type: text/plain, Size: 514 bytes --] *remain in query_page_cache_segment() is over counted by 1, fix it. Signed-off-by: Wu Fengguang <wfg@mail.ustc.edu.cn> --- --- linux-2.6.17-rc4-mm3.orig/mm/readahead.c +++ linux-2.6.17-rc4-mm3/mm/readahead.c @@ -1334,7 +1334,7 @@ static unsigned long query_page_cache_se index = radix_tree_scan_hole_backward(&mapping->page_tree, offset - 1, ra_max); - *remain = offset - index; + *remain = (offset - 1) - index; if (offset == ra->readahead_index && ra_cache_hit_ok(ra)) count = *remain; -- ^ permalink raw reply [flat|nested] 4+ messages in thread
* [patch 4/4] readahead: backward prefetching method - add use case comment @ 2006-05-30 8:40 ` Wu Fengguang 0 siblings, 0 replies; 4+ messages in thread From: Wu Fengguang @ 2006-05-30 8:40 UTC (permalink / raw) To: Andrew Morton; +Cc: linux-kernel, Wu Fengguang [-- Attachment #1: readahead-method-backward-fix-use-case-comment.patch --] [-- Type: text/plain, Size: 583 bytes --] Backward prefetching is vital to structural analysis and some other scientific applications. Comment this use case. Signed-off-by: Wu Fengguang <wfg@mail.ustc.edu.cn> --- --- linux-2.6.17-rc4-mm3.orig/mm/readahead.c +++ linux-2.6.17-rc4-mm3/mm/readahead.c @@ -1540,6 +1540,8 @@ initial_readahead(struct address_space * * Backward prefetching. * * No look-ahead and thrashing safety guard: should be unnecessary. + * + * Important for certain scientific arenas(i.e. structural analysis). */ static int try_read_backward(struct file_ra_state *ra, pgoff_t begin_index, -- ^ permalink raw reply [flat|nested] 4+ messages in thread
* [patch 4/4] readahead: backward prefetching method - add use case comment @ 2006-05-30 8:40 ` Wu Fengguang 0 siblings, 0 replies; 4+ messages in thread From: Wu Fengguang @ 2006-05-30 8:40 UTC (permalink / raw) To: Andrew Morton; +Cc: linux-kernel, Wu Fengguang [-- Attachment #1: readahead-method-backward-fix-use-case-comment.patch --] [-- Type: text/plain, Size: 583 bytes --] Backward prefetching is vital to structural analysis and some other scientific applications. Comment this use case. Signed-off-by: Wu Fengguang <wfg@mail.ustc.edu.cn> --- --- linux-2.6.17-rc4-mm3.orig/mm/readahead.c +++ linux-2.6.17-rc4-mm3/mm/readahead.c @@ -1540,6 +1540,8 @@ initial_readahead(struct address_space * * Backward prefetching. * * No look-ahead and thrashing safety guard: should be unnecessary. + * + * Important for certain scientific arenas(i.e. structural analysis). */ static int try_read_backward(struct file_ra_state *ra, pgoff_t begin_index, -- ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2006-05-30 8:47 UTC | newest] Thread overview: 4+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2006-05-30 8:40 [patch 0/4] Adaptive readahead patchset V14 updates Wu Fengguang 2006-05-30 8:40 ` Wu Fengguang 2006-05-30 8:40 ` [patch 1/4] readahead: state based method - stand-alone size limit code Wu Fengguang 2006-05-30 8:40 ` Wu Fengguang 2006-05-30 8:40 ` [patch 3/4] readahead: context based method - fix *remain counting Wu Fengguang 2006-05-30 8:40 ` Wu Fengguang 2006-05-30 8:40 ` [patch 4/4] readahead: backward prefetching method - add use case comment Wu Fengguang 2006-05-30 8:40 ` Wu Fengguang
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