From 5c43b80577a3dcdd47df9221ef42e5af22c1c641 Mon Sep 17 00:00:00 2001 From: dormando Date: Tue, 20 Jun 2017 17:30:21 -0700 Subject: add a real slab automover algorithm converts the python script to C, more or less. --- slab_automove.c | 150 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 150 insertions(+) create mode 100644 slab_automove.c (limited to 'slab_automove.c') diff --git a/slab_automove.c b/slab_automove.c new file mode 100644 index 0000000..8a66370 --- /dev/null +++ b/slab_automove.c @@ -0,0 +1,150 @@ +/* Copyright 2017 Facebook. + * + * Use and distribution licensed under the BSD license. See + * the LICENSE file for full text. + */ + +/* -*- Mode: C; tab-width: 4; c-basic-offset: 4; indent-tabs-mode: nil -*- */ +#include "memcached.h" +#include "slab_automove.h" +#include +#include + +#define MIN_PAGES_FOR_SOURCE 2 +#define MIN_PAGES_FOR_RECLAIM 2.5 + +struct window_data { + uint64_t age; + uint64_t dirty; + uint64_t evicted; +}; + +typedef struct { + struct window_data *window_data; + uint32_t window_size; + uint32_t window_cur; + double max_age_ratio; + item_stats_automove iam_before[MAX_NUMBER_OF_SLAB_CLASSES]; + item_stats_automove iam_after[MAX_NUMBER_OF_SLAB_CLASSES]; + slab_stats_automove sam_before[MAX_NUMBER_OF_SLAB_CLASSES]; + slab_stats_automove sam_after[MAX_NUMBER_OF_SLAB_CLASSES]; +} slab_automove; + +void *slab_automove_init(uint32_t window_size, double max_age_ratio) { + slab_automove *a = calloc(1, sizeof(slab_automove)); + if (a == NULL) + return NULL; + a->window_data = calloc(window_size * MAX_NUMBER_OF_SLAB_CLASSES, sizeof(struct window_data)); + a->window_size = window_size; + a->max_age_ratio = max_age_ratio; + if (a->window_data == NULL) { + free(a); + return NULL; + } + + // do a dry run to fill the before structs + fill_item_stats_automove(a->iam_before); + fill_slab_stats_automove(a->sam_before); + + return (void *)a; +} + +void slab_automove_free(void *arg) { + slab_automove *a = (slab_automove *)arg; + free(a->window_data); + free(a); +} + +static void window_sum(struct window_data *wd, struct window_data *w, uint32_t size) { + int x; + for (x = 0; x < size; x++) { + struct window_data *d = &wd[x]; + w->age += d->age; + w->dirty += d->dirty; + w->evicted += d->evicted; + } +} + +// TODO: if oldest is dirty, find next oldest. +// still need to base ratio off of absolute age +void slab_automove_run(void *arg, int *src, int *dst) { + slab_automove *a = (slab_automove *)arg; + int n; + struct window_data w_sum; + int oldest = -1; + uint64_t oldest_age = 0; + int youngest = -1; + uint64_t youngest_age = ~0; + bool youngest_evicting = false; + *src = -1; + *dst = -1; + + // fill after structs + fill_item_stats_automove(a->iam_after); + fill_slab_stats_automove(a->sam_after); + a->window_cur++; + + // iterate slabs + for (n = POWER_SMALLEST; n < MAX_NUMBER_OF_SLAB_CLASSES; n++) { + int w_offset = n * a->window_size; + struct window_data *wd = &a->window_data[w_offset + (a->window_cur % a->window_size)]; + memset(wd, 0, sizeof(struct window_data)); + // summarize the window-up-to-now. + memset(&w_sum, 0, sizeof(struct window_data)); + window_sum(&a->window_data[w_offset], &w_sum, a->window_size); + + // if page delta, or evicted delta, mark window dirty + // (or outofmemory) + if (a->iam_after[n].evicted - a->iam_before[n].evicted > 0 || + a->iam_after[n].outofmemory - a->iam_before[n].outofmemory > 0) { + wd->evicted = 1; + wd->dirty = 1; + } + if (a->sam_after[n].total_pages - a->sam_before[n].total_pages > 0) { + wd->dirty = 1; + } + + // set age into window + wd->age = a->iam_after[n].age; + + // grab age as average of window total + uint64_t age = w_sum.age / a->window_size; + + // if > N free chunks and not dirty, make decision. + if (a->sam_after[n].free_chunks > a->sam_after[n].chunks_per_page * MIN_PAGES_FOR_RECLAIM) { + if (w_sum.dirty == 0) { + *src = n; + *dst = 0; + break; + } + } + + // if oldest and have enough pages, is oldest + if (age > oldest_age && a->sam_after[n].total_pages > MIN_PAGES_FOR_SOURCE) { + oldest = n; + oldest_age = age; + } + + // grab evicted count from window + // if > half the window and youngest, mark as youngest + if (age < youngest_age && w_sum.evicted > a->window_size / 2) { + youngest = n; + youngest_age = age; + youngest_evicting = wd->evicted ? true : false; + } + } + + memcpy(a->iam_before, a->iam_after, + sizeof(item_stats_automove) * MAX_NUMBER_OF_SLAB_CLASSES); + memcpy(a->sam_before, a->sam_after, + sizeof(slab_stats_automove) * MAX_NUMBER_OF_SLAB_CLASSES); + // if we have a youngest and oldest, and oldest is outside the ratio, + // also, only make decisions if window has filled once. + if (youngest != -1 && oldest != -1 && a->window_cur > a->window_size) { + if (youngest_age < ((double)oldest_age * a->max_age_ratio) && youngest_evicting) { + *src = oldest; + *dst = youngest; + } + } + return; +} -- cgit v1.2.1