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Re: [Qemu-devel] [PATCH v2 7/8] migration/ram: ensure write persistence
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] [PATCH v2 7/8] migration/ram: ensure write persistence on loading compressed pages to PMEM |
Date: |
Wed, 7 Feb 2018 11:54:06 +0000 |
User-agent: |
Mutt/1.9.1 (2017-09-22) |
* Haozhong Zhang (address@hidden) wrote:
> When loading a compressed page to persistent memory, flush CPU cache
> after the data is decompressed. Combined with a call to pmem_drain()
> at the end of memory loading, we can guarantee those compressed pages
> are persistently loaded to PMEM.
Can you explain why this can use the flush and doesn't need the special
memset?
Dave
> Signed-off-by: Haozhong Zhang <address@hidden>
> ---
> include/qemu/pmem.h | 4 ++++
> migration/ram.c | 16 +++++++++++-----
> 2 files changed, 15 insertions(+), 5 deletions(-)
>
> diff --git a/include/qemu/pmem.h b/include/qemu/pmem.h
> index 77ee1fc4eb..20e3f6e71d 100644
> --- a/include/qemu/pmem.h
> +++ b/include/qemu/pmem.h
> @@ -37,6 +37,10 @@ static inline void *pmem_memset_nodrain(void *pmemdest,
> int c, size_t len)
> return memset(pmemdest, c, len);
> }
>
> +static inline void pmem_flush(const void *addr, size_t len)
> +{
> +}
> +
> static inline void pmem_drain(void)
> {
> }
> diff --git a/migration/ram.c b/migration/ram.c
> index 5a79bbff64..924d2b9537 100644
> --- a/migration/ram.c
> +++ b/migration/ram.c
> @@ -274,6 +274,7 @@ struct DecompressParam {
> void *des;
> uint8_t *compbuf;
> int len;
> + bool is_pmem;
> };
> typedef struct DecompressParam DecompressParam;
>
> @@ -2502,7 +2503,7 @@ static void *do_data_decompress(void *opaque)
> DecompressParam *param = opaque;
> unsigned long pagesize;
> uint8_t *des;
> - int len;
> + int len, rc;
>
> qemu_mutex_lock(¶m->mutex);
> while (!param->quit) {
> @@ -2518,8 +2519,11 @@ static void *do_data_decompress(void *opaque)
> * not a problem because the dirty page will be retransferred
> * and uncompress() won't break the data in other pages.
> */
> - uncompress((Bytef *)des, &pagesize,
> - (const Bytef *)param->compbuf, len);
> + rc = uncompress((Bytef *)des, &pagesize,
> + (const Bytef *)param->compbuf, len);
> + if (rc == Z_OK && param->is_pmem) {
> + pmem_flush(des, len);
> + }
>
> qemu_mutex_lock(&decomp_done_lock);
> param->done = true;
> @@ -2605,7 +2609,8 @@ static void compress_threads_load_cleanup(void)
> }
>
> static void decompress_data_with_multi_threads(QEMUFile *f,
> - void *host, int len)
> + void *host, int len,
> + bool is_pmem)
> {
> int idx, thread_count;
>
> @@ -2619,6 +2624,7 @@ static void decompress_data_with_multi_threads(QEMUFile
> *f,
> qemu_get_buffer(f, decomp_param[idx].compbuf, len);
> decomp_param[idx].des = host;
> decomp_param[idx].len = len;
> + decomp_param[idx].is_pmem = is_pmem;
> qemu_cond_signal(&decomp_param[idx].cond);
> qemu_mutex_unlock(&decomp_param[idx].mutex);
> break;
> @@ -2964,7 +2970,7 @@ static int ram_load(QEMUFile *f, void *opaque, int
> version_id)
> ret = -EINVAL;
> break;
> }
> - decompress_data_with_multi_threads(f, host, len);
> + decompress_data_with_multi_threads(f, host, len, is_pmem);
> break;
>
> case RAM_SAVE_FLAG_XBZRLE:
> --
> 2.14.1
>
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK
- Re: [Qemu-devel] [PATCH v2 5/8] migration/ram: ensure write persistence on loading zero pages to PMEM, (continued)
[Qemu-devel] [PATCH v2 6/8] migration/ram: ensure write persistence on loading normal pages to PMEM, Haozhong Zhang, 2018/02/07
[Qemu-devel] [PATCH v2 7/8] migration/ram: ensure write persistence on loading compressed pages to PMEM, Haozhong Zhang, 2018/02/07
- Re: [Qemu-devel] [PATCH v2 7/8] migration/ram: ensure write persistence on loading compressed pages to PMEM,
Dr. David Alan Gilbert <=
- Re: [Qemu-devel] [PATCH v2 7/8] migration/ram: ensure write persistence on loading compressed pages to PMEM, Haozhong Zhang, 2018/02/07
- Re: [Qemu-devel] [PATCH v2 7/8] migration/ram: ensure write persistence on loading compressed pages to PMEM, Dr. David Alan Gilbert, 2018/02/07
- Re: [Qemu-devel] [PATCH v2 7/8] migration/ram: ensure write persistence on loading compressed pages to PMEM, Haozhong Zhang, 2018/02/07
- Re: [Qemu-devel] [PATCH v2 7/8] migration/ram: ensure write persistence on loading compressed pages to PMEM, Dr. David Alan Gilbert, 2018/02/07
- Re: [Qemu-devel] [PATCH v2 7/8] migration/ram: ensure write persistence on loading compressed pages to PMEM, Dan Williams, 2018/02/07
- Re: [Qemu-devel] [PATCH v2 7/8] migration/ram: ensure write persistence on loading compressed pages to PMEM, Dr. David Alan Gilbert, 2018/02/07
- Re: [Qemu-devel] [PATCH v2 7/8] migration/ram: ensure write persistence on loading compressed pages to PMEM, Dan Williams, 2018/02/07
- Re: [Qemu-devel] [PATCH v2 7/8] migration/ram: ensure write persistence on loading compressed pages to PMEM, Dr. David Alan Gilbert, 2018/02/07
- Re: [Qemu-devel] [PATCH v2 7/8] migration/ram: ensure write persistence on loading compressed pages to PMEM, Dan Williams, 2018/02/07
[Qemu-devel] [PATCH v2 8/8] migration/ram: ensure write persistence on loading xbzrle pages to PMEM, Haozhong Zhang, 2018/02/07