From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e9.ny.us.ibm.com ([32.97.182.139]:39854 "EHLO e9.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1946131Ab2JYPKY (ORCPT ); Thu, 25 Oct 2012 11:10:24 -0400 Received: from /spool/local by e9.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 25 Oct 2012 11:10:23 -0400 From: zwu.kernel@gmail.com To: linux-fsdevel@vger.kernel.org Cc: linux-ext4@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org, linuxram@linux.vnet.ibm.com, viro@zeniv.linux.org.uk, david@fromorbit.com, tytso@mit.edu, cmm@us.ibm.com, Zhi Yong Wu Subject: [RFC v4 06/15] vfs,hot_track: add the function for updating map arrays Date: Thu, 25 Oct 2012 23:08:58 +0800 Message-Id: <1351177747-19389-7-git-send-email-zwu.kernel@gmail.com> In-Reply-To: <1351177747-19389-1-git-send-email-zwu.kernel@gmail.com> References: <1351177747-19389-1-git-send-email-zwu.kernel@gmail.com> Sender: linux-btrfs-owner@vger.kernel.org List-ID: From: Zhi Yong Wu Signed-off-by: Zhi Yong Wu --- fs/hot_tracking.c | 164 +++++++++++++++++++++++++++++++++++++++++++++++++++++ fs/hot_tracking.h | 54 +++++++++++++++++ 2 files changed, 218 insertions(+), 0 deletions(-) diff --git a/fs/hot_tracking.c b/fs/hot_tracking.c index b5568bc..05624ad 100644 --- a/fs/hot_tracking.c +++ b/fs/hot_tracking.c @@ -331,6 +331,170 @@ static void hot_freq_data_update(struct hot_freq_data *freq_data, bool write) } } +static u64 hot_raw_shift(u64 counter, u32 bits, bool dir) +{ + if (dir) + return counter << bits; + else + return counter >> bits; +} + +/* + * hot_temp_calc() is responsible for distilling the six heat + * criteria, which are described in detail in hot_tracking.h) down into a single + * temperature value for the data, which is an integer between 0 + * and HEAT_MAX_VALUE. + * + * To accomplish this, the raw values from the hot_freq_data structure + * are shifted various ways in order to make the temperature calculation more + * or less sensitive to each value. + * + * Once this calibration has happened, we do some additional normalization and + * make sure that everything fits nicely in a u32. From there, we take a very + * rudimentary kind of "average" of each of the values, where the *_COEFF_POWER + * values act as weights for the average. + * + * Finally, we use the HEAT_HASH_BITS value, which determines the size of the + * heat list array, to normalize the temperature to the proper granularity. + */ +u32 hot_temp_calc(struct hot_freq_data *freq_data) +{ + u32 result = 0; + + struct timespec ckt = current_kernel_time(); + u64 cur_time = timespec_to_ns(&ckt); + + u32 nrr_heat = (u32)hot_raw_shift((u64)freq_data->nr_reads, + NRR_MULTIPLIER_POWER, true); + u32 nrw_heat = (u32)hot_raw_shift((u64)freq_data->nr_writes, + NRW_MULTIPLIER_POWER, true); + + u64 ltr_heat = + hot_raw_shift((cur_time - timespec_to_ns(&freq_data->last_read_time)), + LTR_DIVIDER_POWER, false); + u64 ltw_heat = + hot_raw_shift((cur_time - timespec_to_ns(&freq_data->last_write_time)), + LTW_DIVIDER_POWER, false); + + u64 avr_heat = + hot_raw_shift((((u64) -1) - freq_data->avg_delta_reads), + AVR_DIVIDER_POWER, false); + u64 avw_heat = + hot_raw_shift((((u64) -1) - freq_data->avg_delta_writes), + AVW_DIVIDER_POWER, false); + + /* ltr_heat is now guaranteed to be u32 safe */ + if (ltr_heat >= hot_raw_shift((u64) 1, 32, true)) + ltr_heat = 0; + else + ltr_heat = hot_raw_shift((u64) 1, 32, true) - ltr_heat; + + /* ltw_heat is now guaranteed to be u32 safe */ + if (ltw_heat >= hot_raw_shift((u64) 1, 32, true)) + ltw_heat = 0; + else + ltw_heat = hot_raw_shift((u64) 1, 32, true) - ltw_heat; + + /* avr_heat is now guaranteed to be u32 safe */ + if (avr_heat >= hot_raw_shift((u64) 1, 32, true)) + avr_heat = (u32) -1; + + /* avw_heat is now guaranteed to be u32 safe */ + if (avw_heat >= hot_raw_shift((u64) 1, 32, true)) + avw_heat = (u32) -1; + + nrr_heat = (u32)hot_raw_shift((u64)nrr_heat, + (3 - NRR_COEFF_POWER), false); + nrw_heat = (u32)hot_raw_shift((u64)nrw_heat, + (3 - NRW_COEFF_POWER), false); + ltr_heat = hot_raw_shift(ltr_heat, (3 - LTR_COEFF_POWER), false); + ltw_heat = hot_raw_shift(ltw_heat, (3 - LTW_COEFF_POWER), false); + avr_heat = hot_raw_shift(avr_heat, (3 - AVR_COEFF_POWER), false); + avw_heat = hot_raw_shift(avw_heat, (3 - AVW_COEFF_POWER), false); + + result = nrr_heat + nrw_heat + (u32) ltr_heat + + (u32) ltw_heat + (u32) avr_heat + (u32) avw_heat; + + return result; +} + +/* + * Calculate a new temperature and, if necessary, + * move the list_head corresponding to this inode or range + * to the proper list with the new temperature + */ +static void hot_map_array_update(struct hot_freq_data *freq_data, + struct hot_info *root) +{ + struct hot_map_head *buckets, *cur_bucket; + struct hot_comm_item *comm_item; + struct hot_inode_item *he; + struct hot_range_item *hr; + u8 a_temp, b_temp; + u32 temp = 0; + + comm_item = container_of(freq_data, + struct hot_comm_item, hot_freq_data); + + if (freq_data->flags & FREQ_DATA_TYPE_INODE) { + he = container_of(comm_item, + struct hot_inode_item, hot_inode); + buckets = root->heat_inode_map; + + spin_lock(&he->hot_inode.lock); + temp = hot_temp_calc(freq_data); + spin_unlock(&he->hot_inode.lock); + + if (he == NULL) + return; + + spin_lock(&he->hot_inode.lock); + a_temp = temp >> (32 - HEAT_MAP_BITS); + b_temp = freq_data->last_temp >> (32 - HEAT_MAP_BITS); + if (list_empty(&he->hot_inode.n_list) || (a_temp != b_temp)) { + if (!list_empty(&he->hot_inode.n_list)) { + list_del_init(&he->hot_inode.n_list); + root->hot_map_nr--; + } + + cur_bucket = buckets + a_temp; + list_add_tail(&he->hot_inode.n_list, + &cur_bucket->node_list); + root->hot_map_nr++; + freq_data->last_temp = temp; + } + spin_unlock(&he->hot_inode.lock); + } else if (freq_data->flags & FREQ_DATA_TYPE_RANGE) { + hr = container_of(comm_item, + struct hot_range_item, hot_range); + buckets = root->heat_range_map; + + spin_lock(&hr->hot_range.lock); + temp = hot_temp_calc(freq_data); + spin_unlock(&hr->hot_range.lock); + + if (hr == NULL) + return; + + spin_lock(&hr->hot_range.lock); + a_temp = temp >> (32 - HEAT_MAP_BITS); + b_temp = freq_data->last_temp >> (32 - HEAT_MAP_BITS); + if (list_empty(&hr->hot_range.n_list) || (a_temp != b_temp)) { + if (!list_empty(&hr->hot_range.n_list)) { + list_del_init(&hr->hot_range.n_list); + root->hot_map_nr--; + } + + cur_bucket = buckets + a_temp; + list_add_tail(&hr->hot_range.n_list, + &cur_bucket->node_list); + root->hot_map_nr++; + freq_data->last_temp = temp; + } + spin_unlock(&hr->hot_range.lock); + } +} + /* * Initialize inode and range map arrays. */ diff --git a/fs/hot_tracking.h b/fs/hot_tracking.h index 3e5f5d0..be2365c 100644 --- a/fs/hot_tracking.h +++ b/fs/hot_tracking.h @@ -25,8 +25,62 @@ #define FREQ_POWER 4 +/* + * The following comments explain what exactly comprises a unit of heat. + * + * Each of six values of heat are calculated and combined in order to form an + * overall temperature for the data: + * + * NRR - number of reads since mount + * NRW - number of writes since mount + * LTR - time elapsed since last read (ns) + * LTW - time elapsed since last write (ns) + * AVR - average delta between recent reads (ns) + * AVW - average delta between recent writes (ns) + * + * These values are divided (right-shifted) according to the *_DIVIDER_POWER + * values defined below to bring the numbers into a reasonable range. You can + * modify these values to fit your needs. However, each heat unit is a u32 and + * thus maxes out at 2^32 - 1. Therefore, you must choose your dividers quite + * carefully or else they could max out or be stuck at zero quite easily. + * + * (E.g., if you chose AVR_DIVIDER_POWER = 0, nothing less than 4s of atime + * delta would bring the temperature above zero, ever.) + * + * Finally, each value is added to the overall temperature between 0 and 8 + * times, depending on its *_COEFF_POWER value. Note that the coefficients are + * also actually implemented with shifts, so take care to treat these values + * as powers of 2. (I.e., 0 means we'll add it to the temp once; 1 = 2x, etc.) + */ + +/* NRR/NRW heat unit = 2^X accesses */ +#define NRR_MULTIPLIER_POWER 20 +#define NRR_COEFF_POWER 0 +#define NRW_MULTIPLIER_POWER 20 +#define NRW_COEFF_POWER 0 + +/* LTR/LTW heat unit = 2^X ns of age */ +#define LTR_DIVIDER_POWER 30 +#define LTR_COEFF_POWER 1 +#define LTW_DIVIDER_POWER 30 +#define LTW_COEFF_POWER 1 + +/* + * AVR/AVW cold unit = 2^X ns of average delta + * AVR/AVW heat unit = HEAT_MAX_VALUE - cold unit + * + * E.g., data with an average delta between 0 and 2^X ns + * will have a cold value of 0, which means a heat value + * equal to HEAT_MAX_VALUE. + */ +#define AVR_DIVIDER_POWER 40 +#define AVR_COEFF_POWER 0 +#define AVW_DIVIDER_POWER 40 +#define AVW_COEFF_POWER 0 + struct hot_inode_item *hot_inode_item_find(struct hot_info *root, u64 ino); void hot_inode_item_put(struct hot_inode_item *he); +u32 hot_temp_calc(struct hot_freq_data *freq_data); #endif /* __HOT_TRACKING__ */ -- 1.7.6.5