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Re: [PATCH 1/3] migration/ram: Modify the code comment of ram_save_host_


From: Kunkun Jiang
Subject: Re: [PATCH 1/3] migration/ram: Modify the code comment of ram_save_host_page()
Date: Thu, 25 Feb 2021 16:16:36 +0800
User-agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.4.0

On 2021/2/25 6:53, David Edmondson wrote:
On Tuesday, 2021-02-23 at 10:16:43 +08, Kunkun Jiang wrote:

The ram_save_host_page() has been modified several times
since its birth. But the comment hasn't been modified as it should
be. It'd better to modify the comment to explain ram_save_host_page()
more clearly.

Signed-off-by: Keqian Zhu <zhukeqian1@huawei.com>
Signed-off-by: Kunkun Jiang <jiangkunkun@huawei.com>
---
  migration/ram.c | 17 +++++++++--------
  1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/migration/ram.c b/migration/ram.c
index 72143da0ac..fc49c3f898 100644
--- a/migration/ram.c
+++ b/migration/ram.c
@@ -1970,15 +1970,16 @@ static int ram_save_target_page(RAMState *rs, 
PageSearchStatus *pss,
  }
/**
- * ram_save_host_page: save a whole host page
+ * ram_save_host_page: save a whole host page or the rest of a block
   *
- * Starting at *offset send pages up to the end of the current host
- * page. It's valid for the initial offset to point into the middle of
- * a host page in which case the remainder of the hostpage is sent.
- * Only dirty target pages are sent. Note that the host page size may
- * be a huge page for this block.
- * The saving stops at the boundary of the used_length of the block
- * if the RAMBlock isn't a multiple of the host page size.
+ * Starting at pss->page send pages up to the end of the current host
+ * page or the boundary of used_length of the block (if the RAMBlock
+ * isn't a multiple of the host page size). The min one is selected.
+ * Only dirty target pages are sent.
+ *
+ * Note that the host page size may be a huge page for this block, it's
+ * valid for the initial offset to point into the middle of a host page
+ * in which case the remainder of the hostpage is sent.
How about:

* Send dirty pages between pss->page and either the end of that page or
* the used_length of the RAMBlock, whichever is smaller.
*
* Note that if the host page is a huge page, pss->page may be in the
* middle of that page.

Thank you. It looks concise and comprehensive.

Best Regards

Kunkun Jiang

   *
   * Returns the number of pages written or negative on error
   *
--
2.23.0
dme.





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