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Drivers: hv: balloon: Prevent the host from ballooning the guest too low 

Based on the amount of memory being managed set a floor on how low the
guest can be ballooned.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
K. Y. Srinivasan 2013-02-08 15:57:16 -08:00 committed by Greg Kroah-Hartman
parent e500d158fb
commit 1c7db96f6f
1 changed files with 34 additions and 1 deletions
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35
drivers/hv/hv_balloon.c
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@ -523,6 +523,34 @@ static void process_info(struct hv_dynmem_device *dm, struct dm_info_msg *msg)
}
}
unsigned long compute_balloon_floor(void)
{
unsigned long min_pages;
#define MB2PAGES(mb) ((mb) << (20 - PAGE_SHIFT))
/* Simple continuous piecewiese linear function:
* max MiB -> min MiB gradient
* 0 0
* 16 16
* 32 24
* 128 72 (1/2)
* 512 168 (1/4)
* 2048 360 (1/8)
* 8192 552 (1/32)
* 32768 1320
* 131072 4392
*/
if (totalram_pages < MB2PAGES(128))
min_pages = MB2PAGES(8) + (totalram_pages >> 1);
else if (totalram_pages < MB2PAGES(512))
min_pages = MB2PAGES(40) + (totalram_pages >> 2);
else if (totalram_pages < MB2PAGES(2048))
min_pages = MB2PAGES(104) + (totalram_pages >> 3);
else
min_pages = MB2PAGES(296) + (totalram_pages >> 5);
#undef MB2PAGES
return min_pages;
}
/*
* Post our status as it relates memory pressure to the
* host. Host expects the guests to post this status
@ -552,9 +580,14 @@ static void post_status(struct hv_dynmem_device *dm)
* The host expects the guest to report free memory.
* Further, the host expects the pressure information to
* include the ballooned out pages.
* For a given amount of memory that we are managing, we
* need to compute a floor below which we should not balloon.
* Compute this and add it to the pressure report.
*/
status.num_avail = val.freeram;
status.num_committed = vm_memory_committed() + dm->num_pages_ballooned;
status.num_committed = vm_memory_committed() +
dm->num_pages_ballooned +
compute_balloon_floor();
vmbus_sendpacket(dm->dev->channel, &status,
sizeof(struct dm_status),