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Re: [Qemu-devel] [PATCH 10/13 v7] dump: add APIs to operate DataCache
From: |
Laszlo Ersek |
Subject: |
Re: [Qemu-devel] [PATCH 10/13 v7] dump: add APIs to operate DataCache |
Date: |
Thu, 23 Jan 2014 15:50:42 +0100 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20131118 Thunderbird/17.0.11 |
one comment below
On 01/17/14 08:46, qiaonuohan wrote:
> DataCache is used to store data temporarily, then the data will be written to
> vmcore. These functions will be called later when writing data of page to
> vmcore.
>
> Signed-off-by: Qiao Nuohan <address@hidden>
> Reviewed-by: Laszlo Ersek <address@hidden>
> ---
> dump.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++
> include/sysemu/dump.h | 9 +++++++++
> 2 files changed, 56 insertions(+), 0 deletions(-)
>
> diff --git a/dump.c b/dump.c
> index 26a1756..fa183cb 100644
> --- a/dump.c
> +++ b/dump.c
> @@ -1173,6 +1173,53 @@ out:
> return ret;
> }
>
> +static void prepare_data_cache(DataCache *data_cache, DumpState *s,
> + off_t offset)
> +{
> + data_cache->fd = s->fd;
> + data_cache->data_size = 0;
> + data_cache->buf_size = BUFSIZE_DATA_CACHE;
> + data_cache->buf = g_malloc0(BUFSIZE_DATA_CACHE);
> + data_cache->offset = offset;
> +}
> +
> +static int write_cache(DataCache *dc, const void *buf, size_t size,
> + bool flag_sync)
> +{
> + /*
> + * dc->buf_size should not be less than size, otherwise dc will never be
> + * enough
> + */
> + assert(size <= dc->buf_size);
> +
> + /*
> + * if flag_sync is set, synchronize data in dc->buf into vmcore.
> + * otherwise check if the space is enough for caching data in buf, if
> not,
> + * write the data in dc->buf to dc->fd and reset dc->buf
> + */
> + if ((!flag_sync && dc->data_size + size > dc->buf_size) ||
> + (flag_sync && dc->data_size > 0)) {
> + if (write_buffer(dc->fd, dc->offset, dc->buf, dc->data_size) < 0) {
> + return -1;
> + }
> +
> + dc->offset += dc->data_size;
> + dc->data_size = 0;
> + }
> +
> + if (!flag_sync) {
> + memcpy(dc->buf + dc->data_size, buf, size);
> + dc->data_size += size;
> + }
You don't need to make this block conditional on !flag_sync. By removing
that restriction, the function would become more general.
But I assume you don't need that -- I believe you feed all data to this
function with flag_sync==false, then call it one last time with
(flag_sync==false && size==0).
Thanks for adding the assert() and for the type change on "buf".
My R-b stands.
Laszlo
> +
> + return 0;
> +}
> +
> +static void free_data_cache(DataCache *data_cache)
> +{
> + g_free(data_cache->buf);
> +}
> +
> static ram_addr_t get_start_block(DumpState *s)
> {
> GuestPhysBlock *block;
> diff --git a/include/sysemu/dump.h b/include/sysemu/dump.h
> index 6d4d0bc..92a95e4 100644
> --- a/include/sysemu/dump.h
> +++ b/include/sysemu/dump.h
> @@ -41,6 +41,7 @@
> #define DISKDUMP_HEADER_BLOCKS (1)
> #define BUFSIZE_BITMAP (TARGET_PAGE_SIZE)
> #define PFN_BUFBITMAP (CHAR_BIT * BUFSIZE_BITMAP)
> +#define BUFSIZE_DATA_CACHE (TARGET_PAGE_SIZE * 4)
>
> typedef struct ArchDumpInfo {
> int d_machine; /* Architecture */
> @@ -142,6 +143,14 @@ typedef struct QEMU_PACKED KdumpSubHeader64 {
> uint64_t max_mapnr_64; /* header_version 6 and later */
> } KdumpSubHeader64;
>
> +typedef struct DataCache {
> + int fd; /* fd of the file where to write the cached data */
> + uint8_t *buf; /* buffer for cached data */
> + size_t buf_size; /* size of the buf */
> + size_t data_size; /* size of cached data in buf */
> + off_t offset; /* offset of the file */
> +} DataCache;
> +
> struct GuestPhysBlockList; /* memory_mapping.h */
> int cpu_get_dump_info(ArchDumpInfo *info,
> const struct GuestPhysBlockList *guest_phys_blocks);
>
- [Qemu-devel] [PATCH 00/13 v7] Make 'dump-guest-memory' dump in kdump-compressed format, qiaonuohan, 2014/01/17
- [Qemu-devel] [PATCH 01/13 v7] dump: const-qualify the buf of WriteCoreDumpFunction, qiaonuohan, 2014/01/17
- [Qemu-devel] [PATCH 06/13 v7] dump: add support for lzo/snappy, qiaonuohan, 2014/01/17
- [Qemu-devel] [PATCH 07/13 v7] dump: add members to DumpState and init some of them, qiaonuohan, 2014/01/17
- [Qemu-devel] [PATCH 05/13 v7] dump: add API to write elf notes to buffer, qiaonuohan, 2014/01/17
- [Qemu-devel] [PATCH 10/13 v7] dump: add APIs to operate DataCache, qiaonuohan, 2014/01/17
- Re: [Qemu-devel] [PATCH 10/13 v7] dump: add APIs to operate DataCache,
Laszlo Ersek <=
- [Qemu-devel] [PATCH 11/13 v7] dump: add API to write dump pages, qiaonuohan, 2014/01/17
- [Qemu-devel] [PATCH 03/13 v7] dump: add API to write header of flatten format, qiaonuohan, 2014/01/17
- [Qemu-devel] [PATCH 02/13 v7] dump: add argument to write_elfxx_notes, qiaonuohan, 2014/01/17
- [Qemu-devel] [PATCH 09/13 v7] dump: add API to write dump_bitmap, qiaonuohan, 2014/01/17
- [Qemu-devel] [PATCH 08/13 v7] dump: add API to write dump header, qiaonuohan, 2014/01/17