From: Chunhai Guo via Linux-erofs <linux-erofs@lists.ozlabs.org>
To: Gao Xiang <hsiangkao@linux.alibaba.com>,
Chunhai Guo <guochunhai@vivo.com>,
"xiang@kernel.org" <xiang@kernel.org>
Cc: "linux-erofs@lists.ozlabs.org" <linux-erofs@lists.ozlabs.org>,
"huyue2@coolpad.com" <huyue2@coolpad.com>
Subject: Re: [PATCH] erofs: rename per-CPU buffers to global buffer pool and make it configurable
Date: Fri, 22 Mar 2024 07:18:14 +0000 [thread overview]
Message-ID: <4c1cddb2-1d34-4390-a320-49ab65ccf35d@vivo.com> (raw)
In-Reply-To: <916399ab-b166-4bf6-8f68-428c1e6f9cc9@linux.alibaba.com>
Got it. I will send patch v2 as your suggestion.
Thanks,
在 2024/3/22 12:10, Gao Xiang 写道:
>
> On 2024/3/22 11:47, Chunhai Guo wrote:
>> It will cost more time if compressed buffers are allocated on demand for
>> low-latency algorithms (like lz4) so EROFS uses per-CPU buffers to keep
>> compressed data if in-place decompression is unfulfilled. While it is
>> kind of wasteful of memory for a device with hundreds of CPUs, and only
>> a small number of CPUs are concurrently decompressing most of the time.
> a small number of CPUs concurrently decompress most of the time.
>
>> This patch renames it as 'global buffer pool' and makes it configurable.
>> This allows two or more CPUs to share a common buffer to reduce memory
>> occupation.
>>
>> Signed-off-by: Chunhai Guo <guochunhai@vivo.com>
>> Suggested-by: Gao Xiang <xiang@kernel.org>
>> ---
>> fs/erofs/Makefile | 2 +-
>> fs/erofs/decompressor.c | 6 +-
>> fs/erofs/internal.h | 14 ++--
>> fs/erofs/pcpubuf.c | 148 --------------------------------------
>> fs/erofs/super.c | 4 +-
>> fs/erofs/utils.c | 155 ++++++++++++++++++++++++++++++++++++++++
>> 6 files changed, 168 insertions(+), 161 deletions(-)
>> delete mode 100644 fs/erofs/pcpubuf.c
>>
>> diff --git a/fs/erofs/Makefile b/fs/erofs/Makefile
>> index 994d0b9deddf..6cf1504c63e6 100644
>> --- a/fs/erofs/Makefile
>> +++ b/fs/erofs/Makefile
>> @@ -3,7 +3,7 @@
>> obj-$(CONFIG_EROFS_FS) += erofs.o
>> erofs-objs := super.o inode.o data.o namei.o dir.o utils.o sysfs.o
>> erofs-$(CONFIG_EROFS_FS_XATTR) += xattr.o
>> -erofs-$(CONFIG_EROFS_FS_ZIP) += decompressor.o zmap.o zdata.o pcpubuf.o
>> +erofs-$(CONFIG_EROFS_FS_ZIP) += decompressor.o zmap.o zdata.o
>> erofs-$(CONFIG_EROFS_FS_ZIP_LZMA) += decompressor_lzma.o
>> erofs-$(CONFIG_EROFS_FS_ZIP_DEFLATE) += decompressor_deflate.o
>> erofs-$(CONFIG_EROFS_FS_ONDEMAND) += fscache.o
>> diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c
>> index d4cee95af14c..99a344684132 100644
>> --- a/fs/erofs/decompressor.c
>> +++ b/fs/erofs/decompressor.c
>> @@ -54,7 +54,7 @@ static int z_erofs_load_lz4_config(struct super_block *sb,
>> sbi->lz4.max_distance_pages = distance ?
>> DIV_ROUND_UP(distance, PAGE_SIZE) + 1 :
>> LZ4_MAX_DISTANCE_PAGES;
>> - return erofs_pcpubuf_growsize(sbi->lz4.max_pclusterblks);
>> + return erofs_gbuf_growsize(sbi->lz4.max_pclusterblks);
>> }
>>
>> /*
>> @@ -159,7 +159,7 @@ static void *z_erofs_lz4_handle_overlap(struct z_erofs_lz4_decompress_ctx *ctx,
>> docopy:
>> /* Or copy compressed data which can be overlapped to per-CPU buffer */
>> in = rq->in;
>> - src = erofs_get_pcpubuf(ctx->inpages);
>> + src = erofs_get_gbuf(ctx->inpages);
>> if (!src) {
>> DBG_BUGON(1);
>> kunmap_local(inpage);
>> @@ -260,7 +260,7 @@ static int z_erofs_lz4_decompress_mem(struct z_erofs_lz4_decompress_ctx *ctx,
>> } else if (maptype == 1) {
>> vm_unmap_ram(src, ctx->inpages);
>> } else if (maptype == 2) {
>> - erofs_put_pcpubuf(src);
>> + erofs_put_gbuf(src);
>> } else if (maptype != 3) {
>> DBG_BUGON(1);
>> return -EFAULT;
>> diff --git a/fs/erofs/internal.h b/fs/erofs/internal.h
>> index b0409badb017..320d3d0d3526 100644
>> --- a/fs/erofs/internal.h
>> +++ b/fs/erofs/internal.h
>> @@ -471,11 +471,11 @@ int erofs_try_to_free_all_cached_pages(struct erofs_sb_info *sbi,
>> struct erofs_workgroup *egrp);
>> int z_erofs_map_blocks_iter(struct inode *inode, struct erofs_map_blocks *map,
>> int flags);
>> -void *erofs_get_pcpubuf(unsigned int requiredpages);
>> -void erofs_put_pcpubuf(void *ptr);
>> -int erofs_pcpubuf_growsize(unsigned int nrpages);
>> -void __init erofs_pcpubuf_init(void);
>> -void erofs_pcpubuf_exit(void);
>> +void *erofs_get_gbuf(unsigned int requiredpages);
>> +void erofs_put_gbuf(void *ptr);
>> +int erofs_gbuf_growsize(unsigned int nrpages);
>> +void __init erofs_gbuf_init(void);
>> +void erofs_gbuf_exit(void);
>> int erofs_init_managed_cache(struct super_block *sb);
>> int z_erofs_parse_cfgs(struct super_block *sb, struct erofs_super_block *dsb);
>> #else
>> @@ -485,8 +485,8 @@ static inline int erofs_init_shrinker(void) { return 0; }
>> static inline void erofs_exit_shrinker(void) {}
>> static inline int z_erofs_init_zip_subsystem(void) { return 0; }
>> static inline void z_erofs_exit_zip_subsystem(void) {}
>> -static inline void erofs_pcpubuf_init(void) {}
>> -static inline void erofs_pcpubuf_exit(void) {}
>> +static inline void erofs_gbuf_init(void) {}
>> +static inline void erofs_gbuf_exit(void) {}
>> static inline int erofs_init_managed_cache(struct super_block *sb) { return 0; }
>> #endif /* !CONFIG_EROFS_FS_ZIP */
>>
>> diff --git a/fs/erofs/pcpubuf.c b/fs/erofs/pcpubuf.c
>> deleted file mode 100644
>> index c7a4b1d77069..000000000000
>> --- a/fs/erofs/pcpubuf.c
>> +++ /dev/null
>> @@ -1,148 +0,0 @@
>> -// SPDX-License-Identifier: GPL-2.0-only
>> -/*
>> - * Copyright (C) Gao Xiang <xiang@kernel.org>
>> - *
>> - * For low-latency decompression algorithms (e.g. lz4), reserve consecutive
>> - * per-CPU virtual memory (in pages) in advance to store such inplace I/O
>> - * data if inplace decompression is failed (due to unmet inplace margin for
>> - * example).
>> - */
>> -#include "internal.h"
>> -
>> -struct erofs_pcpubuf {
>> - raw_spinlock_t lock;
>> - void *ptr;
>> - struct page **pages;
>> - unsigned int nrpages;
>> -};
>> -
>> -static DEFINE_PER_CPU(struct erofs_pcpubuf, erofs_pcb);
>> -
>> -void *erofs_get_pcpubuf(unsigned int requiredpages)
>> - __acquires(pcb->lock)
>> -{
>> - struct erofs_pcpubuf *pcb = &get_cpu_var(erofs_pcb);
>> -
>> - raw_spin_lock(&pcb->lock);
>> - /* check if the per-CPU buffer is too small */
>> - if (requiredpages > pcb->nrpages) {
>> - raw_spin_unlock(&pcb->lock);
>> - put_cpu_var(erofs_pcb);
>> - /* (for sparse checker) pretend pcb->lock is still taken */
>> - __acquire(pcb->lock);
>> - return NULL;
>> - }
>> - return pcb->ptr;
>> -}
>> -
>> -void erofs_put_pcpubuf(void *ptr) __releases(pcb->lock)
>> -{
>> - struct erofs_pcpubuf *pcb = &per_cpu(erofs_pcb, smp_processor_id());
>> -
>> - DBG_BUGON(pcb->ptr != ptr);
>> - raw_spin_unlock(&pcb->lock);
>> - put_cpu_var(erofs_pcb);
>> -}
>> -
>> -/* the next step: support per-CPU page buffers hotplug */
>> -int erofs_pcpubuf_growsize(unsigned int nrpages)
>> -{
>> - static DEFINE_MUTEX(pcb_resize_mutex);
>> - static unsigned int pcb_nrpages;
>> - struct page *pagepool = NULL;
>> - int delta, cpu, ret, i;
>> -
>> - mutex_lock(&pcb_resize_mutex);
>> - delta = nrpages - pcb_nrpages;
>> - ret = 0;
>> - /* avoid shrinking pcpubuf, since no idea how many fses rely on */
>> - if (delta <= 0)
>> - goto out;
>> -
>> - for_each_possible_cpu(cpu) {
>> - struct erofs_pcpubuf *pcb = &per_cpu(erofs_pcb, cpu);
>> - struct page **pages, **oldpages;
>> - void *ptr, *old_ptr;
>> -
>> - pages = kmalloc_array(nrpages, sizeof(*pages), GFP_KERNEL);
>> - if (!pages) {
>> - ret = -ENOMEM;
>> - break;
>> - }
>> -
>> - for (i = 0; i < nrpages; ++i) {
>> - pages[i] = erofs_allocpage(&pagepool, GFP_KERNEL);
>> - if (!pages[i]) {
>> - ret = -ENOMEM;
>> - oldpages = pages;
>> - goto free_pagearray;
>> - }
>> - }
>> - ptr = vmap(pages, nrpages, VM_MAP, PAGE_KERNEL);
>> - if (!ptr) {
>> - ret = -ENOMEM;
>> - oldpages = pages;
>> - goto free_pagearray;
>> - }
>> - raw_spin_lock(&pcb->lock);
>> - old_ptr = pcb->ptr;
>> - pcb->ptr = ptr;
>> - oldpages = pcb->pages;
>> - pcb->pages = pages;
>> - i = pcb->nrpages;
>> - pcb->nrpages = nrpages;
>> - raw_spin_unlock(&pcb->lock);
>> -
>> - if (!oldpages) {
>> - DBG_BUGON(old_ptr);
>> - continue;
>> - }
>> -
>> - if (old_ptr)
>> - vunmap(old_ptr);
>> -free_pagearray:
>> - while (i)
>> - erofs_pagepool_add(&pagepool, oldpages[--i]);
>> - kfree(oldpages);
>> - if (ret)
>> - break;
>> - }
>> - pcb_nrpages = nrpages;
>> - erofs_release_pages(&pagepool);
>> -out:
>> - mutex_unlock(&pcb_resize_mutex);
>> - return ret;
>> -}
>> -
>> -void __init erofs_pcpubuf_init(void)
>> -{
>> - int cpu;
>> -
>> - for_each_possible_cpu(cpu) {
>> - struct erofs_pcpubuf *pcb = &per_cpu(erofs_pcb, cpu);
>> -
>> - raw_spin_lock_init(&pcb->lock);
>> - }
>> -}
>> -
>> -void erofs_pcpubuf_exit(void)
>> -{
>> - int cpu, i;
>> -
>> - for_each_possible_cpu(cpu) {
>> - struct erofs_pcpubuf *pcb = &per_cpu(erofs_pcb, cpu);
>> -
>> - if (pcb->ptr) {
>> - vunmap(pcb->ptr);
>> - pcb->ptr = NULL;
>> - }
>> - if (!pcb->pages)
>> - continue;
>> -
>> - for (i = 0; i < pcb->nrpages; ++i)
>> - if (pcb->pages[i])
>> - put_page(pcb->pages[i]);
>> - kfree(pcb->pages);
>> - pcb->pages = NULL;
>> - }
>> -}
>> diff --git a/fs/erofs/super.c b/fs/erofs/super.c
>> index 5f60f163bd56..5161923c33fc 100644
>> --- a/fs/erofs/super.c
>> +++ b/fs/erofs/super.c
>> @@ -902,7 +902,7 @@ static int __init erofs_module_init(void)
>> if (err)
>> goto deflate_err;
>>
>> - erofs_pcpubuf_init();
>> + erofs_gbuf_init();
>> err = z_erofs_init_zip_subsystem();
>> if (err)
>> goto zip_err;
>> @@ -945,7 +945,7 @@ static void __exit erofs_module_exit(void)
>> z_erofs_lzma_exit();
>> erofs_exit_shrinker();
>> kmem_cache_destroy(erofs_inode_cachep);
>> - erofs_pcpubuf_exit();
>> + erofs_gbuf_exit();
>> }
>>
>> static int erofs_statfs(struct dentry *dentry, struct kstatfs *buf)
>> diff --git a/fs/erofs/utils.c b/fs/erofs/utils.c
>> index e146d09151af..7bdff1c7ce19 100644
>> --- a/fs/erofs/utils.c
>> +++ b/fs/erofs/utils.c
>> @@ -284,4 +284,159 @@ void erofs_exit_shrinker(void)
>> {
>> shrinker_free(erofs_shrinker_info);
>> }
>> +
>> +struct erofs_gbuf {
> struct z_erofs_gbuf {
>
>> + spinlock_t lock;
>> + void *ptr;
>> + struct page **pages;
>> + unsigned int nrpages, ref;
>> + struct list_head list;
>> +};
>> +
>> +struct erofs_gbufpool {
>> + struct erofs_gbuf *gbuf_array;
>> + unsigned int gbuf_num, gbuf_nrpages;
>> +};
> could we avoid this structure? I think it's only used once:
>
> struct z_erofs_gbuf *z_erofs_gbufpool;
> unsigned int z_erofs_gbuf_count, z_erofs_gbuf_nrpages;
>
> module_param_named(global_buffers, z_erofs_gbuf_count, uint, 0444);
>
>> +
>> +struct erofs_gbufpool z_erofs_gbufpool;
>> +
>> +module_param_named(pcluster_buf_num, z_erofs_gbufpool.gbuf_num, uint, 0444);
>> +
>> +static inline unsigned int erofs_cur_gbuf(void)
> inline here is unnecessary, and
>
> static unsigned int z_erofs_gbuf_id(void)
> {
>
>> +{
>> + return smp_processor_id() % z_erofs_gbufpool.gbuf_num;
>> +}
>> +
>> +void *erofs_get_gbuf(unsigned int requiredpages)
> z_erofs_get_gbuf
>
>> + __acquires(gbuf->lock)
>> +{
>> + struct erofs_gbuf *gbuf;
>> +
>> + gbuf = &z_erofs_gbufpool.gbuf_array[erofs_cur_gbuf()];
>> + spin_lock(&gbuf->lock);
>> + /* check if the buffer is too small */
>> + if (requiredpages > gbuf->nrpages) {
>> + spin_unlock(&gbuf->lock);
>> + /* (for sparse checker) pretend gbuf->lock is still taken */
>> + __acquire(gbuf->lock);
>> + return NULL;
>> + }
>> + return gbuf->ptr;
>> +}
>> +
>> +void erofs_put_gbuf(void *ptr) __releases(gbuf->lock)
> z_erofs_put_gbuf
>
>> +{
>> + struct erofs_gbuf *gbuf;
>> +
>> + gbuf = &z_erofs_gbufpool.gbuf_array[erofs_cur_gbuf()];
>> + DBG_BUGON(gbuf->ptr != ptr);
>> + spin_unlock(&gbuf->lock);
>> +}
>> +
>> +int erofs_gbuf_growsize(unsigned int nrpages)
> z_erofs_get_growsize
>
>> +{
>> + static DEFINE_MUTEX(gbuf_resize_mutex);
>> + struct page *pagepool = NULL;
> Since we just grow global buffers, I think we could just copy
> the old array and fill the rest? so that pagepool is needed
> and we don't touch `struct page` anymore so `folio` is not
> eeded.
>
> But it can be done with a seperate patch.
>
>
>> + int delta, ret, i, j;
>> +
>> + if (!z_erofs_gbufpool.gbuf_array)
>> + return -ENOMEM;
>> +
>> + mutex_lock(&gbuf_resize_mutex);
>> + delta = nrpages - z_erofs_gbufpool.gbuf_nrpages;
>> + ret = 0;
> ret = -EINVAL;
>
>> + /* avoid shrinking pcl_buf, since no idea how many fses rely on */
> /* avoid shrinking gbufs ... */
>
>> + if (delta <= 0)
>> + goto out;
>> +
>> + for (i = 0; i < z_erofs_gbufpool.gbuf_num; ++i) {
>> + struct erofs_gbuf *gbuf = &z_erofs_gbufpool.gbuf_array[i];
>> + struct page **pages, **tmp_pages;
>> + void *ptr, *old_ptr = NULL;
>> +
>> + ret = -ENOMEM;
>> + tmp_pages = kmalloc_array(nrpages, sizeof(*tmp_pages),
>> + GFP_KERNEL);
>> + if (!tmp_pages)
>> + break;
>> + for (j = 0; j < nrpages; ++j) {
>> + tmp_pages[j] = erofs_allocpage(&pagepool, GFP_KERNEL);
>> + if (!tmp_pages[j])
>> + goto free_pagearray;
>> + }
>> + ptr = vmap(tmp_pages, nrpages, VM_MAP, PAGE_KERNEL);
>> + if (!ptr)
>> + goto free_pagearray;
>> +
>> + pages = tmp_pages;
>> + spin_lock(&gbuf->lock);
>> + old_ptr = gbuf->ptr;
>> + gbuf->ptr = ptr;
>> + tmp_pages = gbuf->pages;
>> + gbuf->pages = pages;
>> + j = gbuf->nrpages;
>> + gbuf->nrpages = nrpages;
>> + spin_unlock(&gbuf->lock);
>> + ret = 0;
>> + if (!tmp_pages) {
>> + DBG_BUGON(old_ptr);
>> + continue;
>> + }
>> +
>> + if (old_ptr)
>> + vunmap(old_ptr);
>> +free_pagearray:
>> + while (j)
>> + erofs_pagepool_add(&pagepool, tmp_pages[--j]);
>> + kfree(tmp_pages);
>> + if (ret)
>> + break;
>> + }
>> + z_erofs_gbufpool.gbuf_nrpages = nrpages;
>> + erofs_release_pages(&pagepool);
>> +out:
>> + mutex_unlock(&gbuf_resize_mutex);
>> + return ret;
>> +}
>> +
>> +void __init erofs_gbuf_init(void)
>> +{
>> + if (!z_erofs_gbufpool.gbuf_num)
>> + z_erofs_gbufpool.gbuf_num = num_possible_cpus();
>> + else if (z_erofs_gbufpool.gbuf_num > num_possible_cpus())
>> + z_erofs_gbufpool.gbuf_num = num_possible_cpus();
> unsigned int i = num_possible_cpus();
>
> if (!z_erofs_gbuf_count)
> z_erofs_gbuf_count = cpus;
> else
> z_erofs_gbuf_count = z_erofs_gbuf_count < i ? : i;
>
>
>
>> +
>> + z_erofs_gbufpool.gbuf_array = kmalloc_array(z_erofs_gbufpool.gbuf_num,
>> + sizeof(*z_erofs_gbufpool.gbuf_array),
>> + GFP_KERNEL | __GFP_ZERO);> + if (!z_erofs_gbufpool.gbuf_array) {
>> + erofs_err(NULL, "failed to alloc page for erofs gbuf_array\n");
>
> erofs_err(NULL, "failed to alloate global buffer array");
>
>
>> + return;> + }
>> +
>> + for (int i = 0; i < z_erofs_gbufpool.gbuf_num; ++i)
> please don't use `for (int i..`.
>
> so for (i = 0; i < z_erofs_gbufpool.gbuf_num; ++i)
>
> Thanks,
> Gao Xiang
prev parent reply other threads:[~2024-03-22 7:18 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-22 3:47 [PATCH] erofs: rename per-CPU buffers to global buffer pool and make it configurable Chunhai Guo via Linux-erofs
2024-03-22 4:10 ` Gao Xiang
2024-03-22 7:18 ` Chunhai Guo via Linux-erofs [this message]
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